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  • Variable table or column names.

    - by Frank Computer
    INFORMIX-SQL or any other SQL-based DB: Suppose I have an app where depending on the value of some columns, example: company.code char(3) {abc} company.brach char(2) {01} Can I construct table name "abc01" for inclusion in SELECT * FROM abc01; ? In other words, a variable table name.. same question applies for column names.

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  • What does this pointer-heavy C code do?

    - by justRadojko
    Could someone explain to me what should two following lines do: s.httpheaderline[s.httpheaderlineptr] = *(char *)uip_appdata; ++((char *)uip_appdata); This is taken from uIP code for microcontrollers. s - structure httpheaderline - http packet presented as a string httpheadrlineptr - integer value uip_appdata - received ethernet packet (string) If some more info is needed please let me know. BTW. Eclipse is reporting an error on the second line with message Invalid lvalue in increment so i'm trying to figure out how to solve this.

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  • implicit declaration of

    - by gcc
    int i=0; char **mainp; for(i=0;i<2;++i) { mainp[i]=malloc(sizeof(char)*200); if(!scanf("%[^#],#",mainp[i])) break; if(i<2) scanf("%[^#],#",mainp[i]); } why does gcc send me that warnings warning: implicit declaration of function ‘scanf’ warning: incompatible implicit declaration of built-in function ‘scanf’ warning: ‘mainp’ may be used uninitialized in this function

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  • "Implicit declaration" warning

    - by gcc
    For this code: int i=0; char **mainp; for(i=0;i<2;++i) { mainp[i]=malloc(sizeof(char)*200); if(!scanf("%[^#],#",mainp[i])) break; if(i<2) scanf("%[^#],#",mainp[i]); } GCC emits the warnings: warning: implicit declaration of function ‘scanf’ warning: incompatible implicit declaration of built-in function ‘scanf’ warning: ‘mainp’ may be used uninitialized in this function And I get a segmentation fault at runtime

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  • C#: check if a string start with any character in a list

    - by JoesyXHN
    Hi, I want to check whether a string starts with any character in a list. My current implementation in C# is as follows: char[] columnChars = new char[] { 'A', 'B', 'C', 'D', 'E' }; private bool startWithColumn(string toCheck) { for(int i=0; i<columnChars.Length; i++) if (toCheck.StartsWith(columnChars[i]+"")) { return true; } return false; } I would like to know if any solution is better?

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  • curl problems in c++ class

    - by Danilo
    I read a few articles on c++ / curl here on stackoverflow and assembled the following. The main goal is to handle the whole request in an instance of a class -- and maybe later in a secondary thread. My problem is: "content_" seems to stay empty though its the same addr and HttpFetch.h: class HttpFetch { private: CURL *curl; static size_t handle(char * data, size_t size, size_t nmemb, void * p); size_t handle_impl(char * data, size_t size, size_t nmemb); public: std::string content_; static std::string url_; HttpFetch(std::string url); void start(); std::string data(); }; HttpFetch.cpp: HttpFetch::HttpFetch(std::string url) { curl_global_init(CURL_GLOBAL_ALL); //pretty obvious curl = curl_easy_init(); content_.append("Test"); std::cout << &content_ << "\n"; curl_easy_setopt(curl, CURLOPT_URL, &url); curl_easy_setopt(curl, CURLOPT_WRITEDATA, &content_); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &HttpFetch::handle); //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); //tell curl to output its progress curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); //std::cout << &content_ << "\n"; } void HttpFetch::start() { curl_easy_perform(curl); curl_easy_cleanup(curl); } size_t HttpFetch::handle(char * data, size_t size, size_t nmemb, void * p) { std::string *stuff = reinterpret_cast<std::string*>(p); stuff->append(data, size * nmemb); std::cout << stuff << "\n"; // has content from data in it! return size * nmemb; } main.cpp: #include "HttpFetch.h" int main(int argc, const char * argv[]) { HttpFetch call = *new HttpFetch("http://www.example.com"); call.start(); ::std::cout << call.content_ << "\n" } Thanks in advance

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  • how does sizeof work with array in C++

    - by skydoor
    Hi, I was told the array name is a pointer char a[] = "a" but when sizeof(a) = 2 why not it is a size of pointer here? however when I define it like this char* a ="a"; we get sizeof(a) =4; Well, I think I need more information about how does sizeof work with the array names.... Can anyone elaborate that?

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  • This is a valid C code but not a valid C++ code?

    - by claws
    In some library I'm using (written in C) its StorePGM(image, width, height, filename) char *image; int width, height; char *filename; { // something something } All functions are defined this way. I never seen such function definitions in my life. They seem to be valid to MSVC but when I compile it as C++ it gives errors. What is it? some kind of old version C?

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  • Float to binary in C++

    - by Eric
    Hi, I'm wondering if there is a way to represent a float using a char in C++? For example: int main() { float test = 4.7567; char result = charRepresentation(test); return 0; } I read that probably using bitset I can do it but I'm not pretty sure.

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  • Remove control M from a text file in C

    - by Werner
    Hi, ist is possible? What would be the easiest way? I tried to compare in the input string character to character so if(char([i]=="^M") char[i]="" but it does not work. By the way, if I were able to check it, what is the wistes substitution? to "" ? Thanks

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  • Searching strings C

    - by Skittles
    First time posting here so I'm sorry if I mess up. I need to search a string and return any strings containing the search data with the search data highlighted. If my string is Hi my name is and I searched name it would produce Hi my NAME is This is a quick code I wrote that works but it only works once. If I try and search again it seg faults. I was hoping someone could hint me at a better way to write this because this code is disgusting! void search(char * srcStr, int n){ int cnt = 0, pnt,i = 0; char tmpText[500]; char tmpName[500]; char *ptr, *ptr2, *ptrLast; int num; while(*(node->text+cnt) != '\0'){ //finds length of string cnt++; } for(pnt = 0; pnt < cnt; pnt++){ //copies node->text into a tmp string tmpText[pnt] = *(node->text+pnt); } tmpText[pnt+1] = '\0'; //prints up to first occurrence of srcStr ptr = strcasestr(tmpText, srcStr); for(num = 0; num < ptr-tmpText; num++){ printf("%c",tmpText[num]); } //prints first occurrence of srcStr in capitals for(num = 0; num < n; num++){ printf("%c",toupper(tmpText[ptr-tmpText+num])); } ptr2 = strcasestr((ptr+n),srcStr); for(num = (ptr-tmpText+n); num < (ptr2-tmpText); num++){ printf("%c",tmpText[num]); } while((ptr = strcasestr((ptr+n), srcStr)) != NULL){ ptr2 = strcasestr((ptr+n),srcStr); for(num = (ptr-tmpText+n); num < (ptr2-tmpText); num++){ printf("%c",tmpText[num]); } for(num = 0; num < n; num++){ printf("%c",toupper(tmpText[ptr-tmpText+num])); } ptrLast = ptr; } //prints remaining string after last occurrence for(num = (ptrLast-tmpText+n); num < cnt; num++){ printf("%c",tmpText[num]); } }

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  • Convert __declspec to _export C++

    - by SroMah
    Hi, I am converting the following function. But the new converted function is not executed. Any ideas? Old Function extern "C" DWORD __declspec(dllexport) FAR MyFunc (char *value1, int *value2) New Function extern "C" DWORD _export FAR MyFunc (char *value1, int *value2)

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  • Return an empty C-String

    - by Evorlor
    Simple Question: How do you return an empty C-String with as little code as possible? I have code that needs to return an empty char*. I am looking for something along the lines of return "";. I know there are several ways to do this, but I am looking for the most efficient way possible. Using return ""; gives warning: conversion from string literal to 'char *' is deprecated [-Wdeprecated-writable-strings] Thanks!

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  • Plan Caching and Query Memory Part II (Hash Match) – When not to use stored procedure - Most common performance mistake SQL Server developers make.

    - by sqlworkshops
    SQL Server estimates Memory requirement at compile time, when stored procedure or other plan caching mechanisms like sp_executesql or prepared statement are used, the memory requirement is estimated based on first set of execution parameters. This is a common reason for spill over tempdb and hence poor performance. Common memory allocating queries are that perform Sort and do Hash Match operations like Hash Join or Hash Aggregation or Hash Union. This article covers Hash Match operations with examples. It is recommended to read Plan Caching and Query Memory Part I before this article which covers an introduction and Query memory for Sort. In most cases it is cheaper to pay for the compilation cost of dynamic queries than huge cost for spill over tempdb, unless memory requirement for a query does not change significantly based on predicates.   This article covers underestimation / overestimation of memory for Hash Match operation. Plan Caching and Query Memory Part I covers underestimation / overestimation for Sort. It is important to note that underestimation of memory for Sort and Hash Match operations lead to spill over tempdb and hence negatively impact performance. Overestimation of memory affects the memory needs of other concurrently executing queries. In addition, it is important to note, with Hash Match operations, overestimation of memory can actually lead to poor performance.   To read additional articles I wrote click here.   The best way to learn is to practice. To create the below tables and reproduce the behavior, join the mailing list by using this link: www.sqlworkshops.com/ml and I will send you the table creation script. Most of these concepts are also covered in our webcasts: www.sqlworkshops.com/webcasts  Let’s create a Customer’s State table that has 99% of customers in NY and the rest 1% in WA.Customers table used in Part I of this article is also used here.To observe Hash Warning, enable 'Hash Warning' in SQL Profiler under Events 'Errors and Warnings'. --Example provided by www.sqlworkshops.com drop table CustomersState go create table CustomersState (CustomerID int primary key, Address char(200), State char(2)) go insert into CustomersState (CustomerID, Address) select CustomerID, 'Address' from Customers update CustomersState set State = 'NY' where CustomerID % 100 != 1 update CustomersState set State = 'WA' where CustomerID % 100 = 1 go update statistics CustomersState with fullscan go   Let’s create a stored procedure that joins customers with CustomersState table with a predicate on State. --Example provided by www.sqlworkshops.com create proc CustomersByState @State char(2) as begin declare @CustomerID int select @CustomerID = e.CustomerID from Customers e inner join CustomersState es on (e.CustomerID = es.CustomerID) where es.State = @State option (maxdop 1) end go  Let’s execute the stored procedure first with parameter value ‘WA’ – which will select 1% of data. set statistics time on go --Example provided by www.sqlworkshops.com exec CustomersByState 'WA' goThe stored procedure took 294 ms to complete.  The stored procedure was granted 6704 KB based on 8000 rows being estimated.  The estimated number of rows, 8000 is similar to actual number of rows 8000 and hence the memory estimation should be ok.  There was no Hash Warning in SQL Profiler. To observe Hash Warning, enable 'Hash Warning' in SQL Profiler under Events 'Errors and Warnings'.   Now let’s execute the stored procedure with parameter value ‘NY’ – which will select 99% of data. -Example provided by www.sqlworkshops.com exec CustomersByState 'NY' go  The stored procedure took 2922 ms to complete.   The stored procedure was granted 6704 KB based on 8000 rows being estimated.    The estimated number of rows, 8000 is way different from the actual number of rows 792000 because the estimation is based on the first set of parameter value supplied to the stored procedure which is ‘WA’ in our case. This underestimation will lead to spill over tempdb, resulting in poor performance.   There was Hash Warning (Recursion) in SQL Profiler. To observe Hash Warning, enable 'Hash Warning' in SQL Profiler under Events 'Errors and Warnings'.   Let’s recompile the stored procedure and then let’s first execute the stored procedure with parameter value ‘NY’.  In a production instance it is not advisable to use sp_recompile instead one should use DBCC FREEPROCCACHE (plan_handle). This is due to locking issues involved with sp_recompile, refer to our webcasts, www.sqlworkshops.com/webcasts for further details.   exec sp_recompile CustomersByState go --Example provided by www.sqlworkshops.com exec CustomersByState 'NY' go  Now the stored procedure took only 1046 ms instead of 2922 ms.   The stored procedure was granted 146752 KB of memory. The estimated number of rows, 792000 is similar to actual number of rows of 792000. Better performance of this stored procedure execution is due to better estimation of memory and avoiding spill over tempdb.   There was no Hash Warning in SQL Profiler.   Now let’s execute the stored procedure with parameter value ‘WA’. --Example provided by www.sqlworkshops.com exec CustomersByState 'WA' go  The stored procedure took 351 ms to complete, higher than the previous execution time of 294 ms.    This stored procedure was granted more memory (146752 KB) than necessary (6704 KB) based on parameter value ‘NY’ for estimation (792000 rows) instead of parameter value ‘WA’ for estimation (8000 rows). This is because the estimation is based on the first set of parameter value supplied to the stored procedure which is ‘NY’ in this case. This overestimation leads to poor performance of this Hash Match operation, it might also affect the performance of other concurrently executing queries requiring memory and hence overestimation is not recommended.     The estimated number of rows, 792000 is much more than the actual number of rows of 8000.  Intermediate Summary: This issue can be avoided by not caching the plan for memory allocating queries. Other possibility is to use recompile hint or optimize for hint to allocate memory for predefined data range.Let’s recreate the stored procedure with recompile hint. --Example provided by www.sqlworkshops.com drop proc CustomersByState go create proc CustomersByState @State char(2) as begin declare @CustomerID int select @CustomerID = e.CustomerID from Customers e inner join CustomersState es on (e.CustomerID = es.CustomerID) where es.State = @State option (maxdop 1, recompile) end go  Let’s execute the stored procedure initially with parameter value ‘WA’ and then with parameter value ‘NY’. --Example provided by www.sqlworkshops.com exec CustomersByState 'WA' go exec CustomersByState 'NY' go  The stored procedure took 297 ms and 1102 ms in line with previous optimal execution times.   The stored procedure with parameter value ‘WA’ has good estimation like before.   Estimated number of rows of 8000 is similar to actual number of rows of 8000.   The stored procedure with parameter value ‘NY’ also has good estimation and memory grant like before because the stored procedure was recompiled with current set of parameter values.  Estimated number of rows of 792000 is similar to actual number of rows of 792000.    The compilation time and compilation CPU of 1 ms is not expensive in this case compared to the performance benefit.   There was no Hash Warning in SQL Profiler.   Let’s recreate the stored procedure with optimize for hint of ‘NY’. --Example provided by www.sqlworkshops.com drop proc CustomersByState go create proc CustomersByState @State char(2) as begin declare @CustomerID int select @CustomerID = e.CustomerID from Customers e inner join CustomersState es on (e.CustomerID = es.CustomerID) where es.State = @State option (maxdop 1, optimize for (@State = 'NY')) end go  Let’s execute the stored procedure initially with parameter value ‘WA’ and then with parameter value ‘NY’. --Example provided by www.sqlworkshops.com exec CustomersByState 'WA' go exec CustomersByState 'NY' go  The stored procedure took 353 ms with parameter value ‘WA’, this is much slower than the optimal execution time of 294 ms we observed previously. This is because of overestimation of memory. The stored procedure with parameter value ‘NY’ has optimal execution time like before.   The stored procedure with parameter value ‘WA’ has overestimation of rows because of optimize for hint value of ‘NY’.   Unlike before, more memory was estimated to this stored procedure based on optimize for hint value ‘NY’.    The stored procedure with parameter value ‘NY’ has good estimation because of optimize for hint value of ‘NY’. Estimated number of rows of 792000 is similar to actual number of rows of 792000.   Optimal amount memory was estimated to this stored procedure based on optimize for hint value ‘NY’.   There was no Hash Warning in SQL Profiler.   This article covers underestimation / overestimation of memory for Hash Match operation. Plan Caching and Query Memory Part I covers underestimation / overestimation for Sort. It is important to note that underestimation of memory for Sort and Hash Match operations lead to spill over tempdb and hence negatively impact performance. Overestimation of memory affects the memory needs of other concurrently executing queries. In addition, it is important to note, with Hash Match operations, overestimation of memory can actually lead to poor performance.   Summary: Cached plan might lead to underestimation or overestimation of memory because the memory is estimated based on first set of execution parameters. It is recommended not to cache the plan if the amount of memory required to execute the stored procedure has a wide range of possibilities. One can mitigate this by using recompile hint, but that will lead to compilation overhead. However, in most cases it might be ok to pay for compilation rather than spilling sort over tempdb which could be very expensive compared to compilation cost. The other possibility is to use optimize for hint, but in case one sorts more data than hinted by optimize for hint, this will still lead to spill. On the other side there is also the possibility of overestimation leading to unnecessary memory issues for other concurrently executing queries. In case of Hash Match operations, this overestimation of memory might lead to poor performance. When the values used in optimize for hint are archived from the database, the estimation will be wrong leading to worst performance, so one has to exercise caution before using optimize for hint, recompile hint is better in this case.   I explain these concepts with detailed examples in my webcasts (www.sqlworkshops.com/webcasts), I recommend you to watch them. The best way to learn is to practice. To create the above tables and reproduce the behavior, join the mailing list at www.sqlworkshops.com/ml and I will send you the relevant SQL Scripts.  Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.   Disclaimer and copyright information:This article refers to organizations and products that may be the trademarks or registered trademarks of their various owners. Copyright of this article belongs to R Meyyappan / www.sqlworkshops.com. You may freely use the ideas and concepts discussed in this article with acknowledgement (www.sqlworkshops.com), but you may not claim any of it as your own work. This article is for informational purposes only; you use any of the suggestions given here entirely at your own risk.   R Meyyappan [email protected] LinkedIn: http://at.linkedin.com/in/rmeyyappan

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  • Very different I/O performance in C++ on Windows

    - by Mr.Gate
    Hi all, I'm a new user and my english is not so good so I hope to be clear. We're facing a performance problem using large files (1GB or more) expecially (as it seems) when you try to grow them in size. Anyway... to verify our sensations we tryed the following (on Win 7 64Bit, 4core, 8GB Ram, 32 bit code compiled with VC2008) a) Open an unexisting file. Write it from the beginning up to 1Gb in 1Mb slots. Now you have a 1Gb file. Now randomize 10000 positions within that file, seek to that position and write 50 bytes in each position, no matter what you write. Close the file and look at the results. Time to create the file is quite fast (about 0.3"), time to write 10000 times is fast all the same (about 0.03"). Very good, this is the beginnig. Now try something else... b) Open an unexisting file, seek to 1Gb-1byte and write just 1 byte. Now you have another 1Gb file. Follow the next steps exactly same way of case 'a', close the file and look at the results. Time to create the file is the faster you can imagine (about 0.00009") but write time is something you can't believe.... about 90"!!!!! b.1) Open an unexisting file, don't write any byte. Act as before, ramdomizing, seeking and writing, close the file and look at the result. Time to write is long all the same: about 90"!!!!! Ok... this is quite amazing. But there's more! c) Open again the file you crated in case 'a', don't truncate it... randomize again 10000 positions and act as before. You're fast as before, about 0,03" to write 10000 times. This sounds Ok... try another step. d) Now open the file you created in case 'b', don't truncate it... randomize again 10000 positions and act as before. You're slow again and again, but the time is reduced to... 45"!! Maybe, trying again, the time will reduce. I actually wonder why... Any Idea? The following is part of the code I used to test what I told in previuos cases (you'll have to change someting in order to have a clean compilation, I just cut & paste from some source code, sorry). The sample can read and write, in random, ordered or reverse ordered mode, but write only in random order is the clearest test. We tryed using std::fstream but also using directly CreateFile(), WriteFile() and so on the results are the same (even if std::fstream is actually a little slower). Parameters for case 'a' = -f_tempdir_\casea.dat -n10000 -t -p -w Parameters for case 'b' = -f_tempdir_\caseb.dat -n10000 -t -v -w Parameters for case 'b.1' = -f_tempdir_\caseb.dat -n10000 -t -w Parameters for case 'c' = -f_tempdir_\casea.dat -n10000 -w Parameters for case 'd' = -f_tempdir_\caseb.dat -n10000 -w Run the test (and even others) and see... // iotest.cpp : Defines the entry point for the console application. // #include <windows.h> #include <iostream> #include <set> #include <vector> #include "stdafx.h" double RealTime_Microsecs() { LARGE_INTEGER fr = {0, 0}; LARGE_INTEGER ti = {0, 0}; double time = 0.0; QueryPerformanceCounter(&ti); QueryPerformanceFrequency(&fr); time = (double) ti.QuadPart / (double) fr.QuadPart; return time; } int main(int argc, char* argv[]) { std::string sFileName ; size_t stSize, stTimes, stBytes ; int retval = 0 ; char *p = NULL ; char *pPattern = NULL ; char *pReadBuf = NULL ; try { // Default stSize = 1<<30 ; // 1Gb stTimes = 1000 ; stBytes = 50 ; bool bTruncate = false ; bool bPre = false ; bool bPreFast = false ; bool bOrdered = false ; bool bReverse = false ; bool bWriteOnly = false ; // Comsumo i parametri for(int index=1; index < argc; ++index) { if ( '-' != argv[index][0] ) throw ; switch(argv[index][1]) { case 'f': sFileName = argv[index]+2 ; break ; case 's': stSize = xw::str::strtol(argv[index]+2) ; break ; case 'n': stTimes = xw::str::strtol(argv[index]+2) ; break ; case 'b':stBytes = xw::str::strtol(argv[index]+2) ; break ; case 't': bTruncate = true ; break ; case 'p' : bPre = true, bPreFast = false ; break ; case 'v' : bPreFast = true, bPre = false ; break ; case 'o' : bOrdered = true, bReverse = false ; break ; case 'r' : bReverse = true, bOrdered = false ; break ; case 'w' : bWriteOnly = true ; break ; default: throw ; break ; } } if ( sFileName.empty() ) { std::cout << "Usage: -f<File Name> -s<File Size> -n<Number of Reads and Writes> -b<Bytes per Read and Write> -t -p -v -o -r -w" << std::endl ; std::cout << "-t truncates the file, -p pre load the file, -v pre load 'veloce', -o writes in order mode, -r write in reverse order mode, -w Write Only" << std::endl ; std::cout << "Default: 1Gb, 1000 times, 50 bytes" << std::endl ; throw ; } if ( !stSize || !stTimes || !stBytes ) { std::cout << "Invalid Parameters" << std::endl ; return -1 ; } size_t stBestSize = 0x00100000 ; std::fstream fFile ; fFile.open(sFileName.c_str(), std::ios_base::binary|std::ios_base::out|std::ios_base::in|(bTruncate?std::ios_base::trunc:0)) ; p = new char[stBestSize] ; pPattern = new char[stBytes] ; pReadBuf = new char[stBytes] ; memset(p, 0, stBestSize) ; memset(pPattern, (int)(stBytes&0x000000ff), stBytes) ; double dTime = RealTime_Microsecs() ; size_t stCopySize, stSizeToCopy = stSize ; if ( bPre ) { do { stCopySize = std::min(stSizeToCopy, stBestSize) ; fFile.write(p, stCopySize) ; stSizeToCopy -= stCopySize ; } while (stSizeToCopy) ; std::cout << "Creating time is: " << xw::str::itoa(RealTime_Microsecs()-dTime, 5, 'f') << std::endl ; } else if ( bPreFast ) { fFile.seekp(stSize-1) ; fFile.write(p, 1) ; std::cout << "Creating Fast time is: " << xw::str::itoa(RealTime_Microsecs()-dTime, 5, 'f') << std::endl ; } size_t stPos ; ::srand((unsigned int)dTime) ; double dReadTime, dWriteTime ; stCopySize = stTimes ; std::vector<size_t> inVect ; std::vector<size_t> outVect ; std::set<size_t> outSet ; std::set<size_t> inSet ; // Prepare vector and set do { stPos = (size_t)(::rand()<<16) % stSize ; outVect.push_back(stPos) ; outSet.insert(stPos) ; stPos = (size_t)(::rand()<<16) % stSize ; inVect.push_back(stPos) ; inSet.insert(stPos) ; } while (--stCopySize) ; // Write & read using vectors if ( !bReverse && !bOrdered ) { std::vector<size_t>::iterator outI, inI ; outI = outVect.begin() ; inI = inVect.begin() ; stCopySize = stTimes ; dReadTime = 0.0 ; dWriteTime = 0.0 ; do { dTime = RealTime_Microsecs() ; fFile.seekp(*outI) ; fFile.write(pPattern, stBytes) ; dWriteTime += RealTime_Microsecs() - dTime ; ++outI ; if ( !bWriteOnly ) { dTime = RealTime_Microsecs() ; fFile.seekg(*inI) ; fFile.read(pReadBuf, stBytes) ; dReadTime += RealTime_Microsecs() - dTime ; ++inI ; } } while (--stCopySize) ; std::cout << "Write time is " << xw::str::itoa(dWriteTime, 5, 'f') << " (Ave: " << xw::str::itoa(dWriteTime/stTimes, 10, 'f') << ")" << std::endl ; if ( !bWriteOnly ) { std::cout << "Read time is " << xw::str::itoa(dReadTime, 5, 'f') << " (Ave: " << xw::str::itoa(dReadTime/stTimes, 10, 'f') << ")" << std::endl ; } } // End // Write in order if ( bOrdered ) { std::set<size_t>::iterator i = outSet.begin() ; dWriteTime = 0.0 ; stCopySize = 0 ; for(; i != outSet.end(); ++i) { stPos = *i ; dTime = RealTime_Microsecs() ; fFile.seekp(stPos) ; fFile.write(pPattern, stBytes) ; dWriteTime += RealTime_Microsecs() - dTime ; ++stCopySize ; } std::cout << "Ordered Write time is " << xw::str::itoa(dWriteTime, 5, 'f') << " in " << xw::str::itoa(stCopySize) << " (Ave: " << xw::str::itoa(dWriteTime/stCopySize, 10, 'f') << ")" << std::endl ; if ( !bWriteOnly ) { i = inSet.begin() ; dReadTime = 0.0 ; stCopySize = 0 ; for(; i != inSet.end(); ++i) { stPos = *i ; dTime = RealTime_Microsecs() ; fFile.seekg(stPos) ; fFile.read(pReadBuf, stBytes) ; dReadTime += RealTime_Microsecs() - dTime ; ++stCopySize ; } std::cout << "Ordered Read time is " << xw::str::itoa(dReadTime, 5, 'f') << " in " << xw::str::itoa(stCopySize) << " (Ave: " << xw::str::itoa(dReadTime/stCopySize, 10, 'f') << ")" << std::endl ; } }// End // Write in reverse order if ( bReverse ) { std::set<size_t>::reverse_iterator i = outSet.rbegin() ; dWriteTime = 0.0 ; stCopySize = 0 ; for(; i != outSet.rend(); ++i) { stPos = *i ; dTime = RealTime_Microsecs() ; fFile.seekp(stPos) ; fFile.write(pPattern, stBytes) ; dWriteTime += RealTime_Microsecs() - dTime ; ++stCopySize ; } std::cout << "Reverse ordered Write time is " << xw::str::itoa(dWriteTime, 5, 'f') << " in " << xw::str::itoa(stCopySize) << " (Ave: " << xw::str::itoa(dWriteTime/stCopySize, 10, 'f') << ")" << std::endl ; if ( !bWriteOnly ) { i = inSet.rbegin() ; dReadTime = 0.0 ; stCopySize = 0 ; for(; i != inSet.rend(); ++i) { stPos = *i ; dTime = RealTime_Microsecs() ; fFile.seekg(stPos) ; fFile.read(pReadBuf, stBytes) ; dReadTime += RealTime_Microsecs() - dTime ; ++stCopySize ; } std::cout << "Reverse ordered Read time is " << xw::str::itoa(dReadTime, 5, 'f') << " in " << xw::str::itoa(stCopySize) << " (Ave: " << xw::str::itoa(dReadTime/stCopySize, 10, 'f') << ")" << std::endl ; } }// End dTime = RealTime_Microsecs() ; fFile.close() ; std::cout << "Flush/Close Time is " << xw::str::itoa(RealTime_Microsecs()-dTime, 5, 'f') << std::endl ; std::cout << "Program Terminated" << std::endl ; } catch(...) { std::cout << "Something wrong or wrong parameters" << std::endl ; retval = -1 ; } if ( p ) delete []p ; if ( pPattern ) delete []pPattern ; if ( pReadBuf ) delete []pReadBuf ; return retval ; }

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  • Very different IO performance in C/C++

    - by Roberto Tirabassi
    Hi all, I'm a new user and my english is not so good so I hope to be clear. We're facing a performance problem using large files (1GB or more) expecially (as it seems) when you try to grow them in size. Anyway... to verify our sensations we tryed the following (on Win 7 64Bit, 4core, 8GB Ram, 32 bit code compiled with VC2008) a) Open an unexisting file. Write it from the beginning up to 1Gb in 1Mb slots. Now you have a 1Gb file. Now randomize 10000 positions within that file, seek to that position and write 50 bytes in each position, no matter what you write. Close the file and look at the results. Time to create the file is quite fast (about 0.3"), time to write 10000 times is fast all the same (about 0.03"). Very good, this is the beginnig. Now try something else... b) Open an unexisting file, seek to 1Gb-1byte and write just 1 byte. Now you have another 1Gb file. Follow the next steps exactly same way of case 'a', close the file and look at the results. Time to create the file is the faster you can imagine (about 0.00009") but write time is something you can't believe.... about 90"!!!!! b.1) Open an unexisting file, don't write any byte. Act as before, ramdomizing, seeking and writing, close the file and look at the result. Time to write is long all the same: about 90"!!!!! Ok... this is quite amazing. But there's more! c) Open again the file you crated in case 'a', don't truncate it... randomize again 10000 positions and act as before. You're fast as before, about 0,03" to write 10000 times. This sounds Ok... try another step. d) Now open the file you created in case 'b', don't truncate it... randomize again 10000 positions and act as before. You're slow again and again, but the time is reduced to... 45"!! Maybe, trying again, the time will reduce. I actually wonder why... Any Idea? The following is part of the code I used to test what I told in previuos cases (you'll have to change someting in order to have a clean compilation, I just cut & paste from some source code, sorry). The sample can read and write, in random, ordered or reverse ordered mode, but write only in random order is the clearest test. We tryed using std::fstream but also using directly CreateFile(), WriteFile() and so on the results are the same (even if std::fstream is actually a little slower). Parameters for case 'a' = -f_tempdir_\casea.dat -n10000 -t -p -w Parameters for case 'b' = -f_tempdir_\caseb.dat -n10000 -t -v -w Parameters for case 'b.1' = -f_tempdir_\caseb.dat -n10000 -t -w Parameters for case 'c' = -f_tempdir_\casea.dat -n10000 -w Parameters for case 'd' = -f_tempdir_\caseb.dat -n10000 -w Run the test (and even others) and see... // iotest.cpp : Defines the entry point for the console application. // #include <windows.h> #include <iostream> #include <set> #include <vector> #include "stdafx.h" double RealTime_Microsecs() { LARGE_INTEGER fr = {0, 0}; LARGE_INTEGER ti = {0, 0}; double time = 0.0; QueryPerformanceCounter(&ti); QueryPerformanceFrequency(&fr); time = (double) ti.QuadPart / (double) fr.QuadPart; return time; } int main(int argc, char* argv[]) { std::string sFileName ; size_t stSize, stTimes, stBytes ; int retval = 0 ; char *p = NULL ; char *pPattern = NULL ; char *pReadBuf = NULL ; try { // Default stSize = 1<<30 ; // 1Gb stTimes = 1000 ; stBytes = 50 ; bool bTruncate = false ; bool bPre = false ; bool bPreFast = false ; bool bOrdered = false ; bool bReverse = false ; bool bWriteOnly = false ; // Comsumo i parametri for(int index=1; index < argc; ++index) { if ( '-' != argv[index][0] ) throw ; switch(argv[index][1]) { case 'f': sFileName = argv[index]+2 ; break ; case 's': stSize = xw::str::strtol(argv[index]+2) ; break ; case 'n': stTimes = xw::str::strtol(argv[index]+2) ; break ; case 'b':stBytes = xw::str::strtol(argv[index]+2) ; break ; case 't': bTruncate = true ; break ; case 'p' : bPre = true, bPreFast = false ; break ; case 'v' : bPreFast = true, bPre = false ; break ; case 'o' : bOrdered = true, bReverse = false ; break ; case 'r' : bReverse = true, bOrdered = false ; break ; case 'w' : bWriteOnly = true ; break ; default: throw ; break ; } } if ( sFileName.empty() ) { std::cout << "Usage: -f<File Name> -s<File Size> -n<Number of Reads and Writes> -b<Bytes per Read and Write> -t -p -v -o -r -w" << std::endl ; std::cout << "-t truncates the file, -p pre load the file, -v pre load 'veloce', -o writes in order mode, -r write in reverse order mode, -w Write Only" << std::endl ; std::cout << "Default: 1Gb, 1000 times, 50 bytes" << std::endl ; throw ; } if ( !stSize || !stTimes || !stBytes ) { std::cout << "Invalid Parameters" << std::endl ; return -1 ; } size_t stBestSize = 0x00100000 ; std::fstream fFile ; fFile.open(sFileName.c_str(), std::ios_base::binary|std::ios_base::out|std::ios_base::in|(bTruncate?std::ios_base::trunc:0)) ; p = new char[stBestSize] ; pPattern = new char[stBytes] ; pReadBuf = new char[stBytes] ; memset(p, 0, stBestSize) ; memset(pPattern, (int)(stBytes&0x000000ff), stBytes) ; double dTime = RealTime_Microsecs() ; size_t stCopySize, stSizeToCopy = stSize ; if ( bPre ) { do { stCopySize = std::min(stSizeToCopy, stBestSize) ; fFile.write(p, stCopySize) ; stSizeToCopy -= stCopySize ; } while (stSizeToCopy) ; std::cout << "Creating time is: " << xw::str::itoa(RealTime_Microsecs()-dTime, 5, 'f') << std::endl ; } else if ( bPreFast ) { fFile.seekp(stSize-1) ; fFile.write(p, 1) ; std::cout << "Creating Fast time is: " << xw::str::itoa(RealTime_Microsecs()-dTime, 5, 'f') << std::endl ; } size_t stPos ; ::srand((unsigned int)dTime) ; double dReadTime, dWriteTime ; stCopySize = stTimes ; std::vector<size_t> inVect ; std::vector<size_t> outVect ; std::set<size_t> outSet ; std::set<size_t> inSet ; // Prepare vector and set do { stPos = (size_t)(::rand()<<16) % stSize ; outVect.push_back(stPos) ; outSet.insert(stPos) ; stPos = (size_t)(::rand()<<16) % stSize ; inVect.push_back(stPos) ; inSet.insert(stPos) ; } while (--stCopySize) ; // Write & read using vectors if ( !bReverse && !bOrdered ) { std::vector<size_t>::iterator outI, inI ; outI = outVect.begin() ; inI = inVect.begin() ; stCopySize = stTimes ; dReadTime = 0.0 ; dWriteTime = 0.0 ; do { dTime = RealTime_Microsecs() ; fFile.seekp(*outI) ; fFile.write(pPattern, stBytes) ; dWriteTime += RealTime_Microsecs() - dTime ; ++outI ; if ( !bWriteOnly ) { dTime = RealTime_Microsecs() ; fFile.seekg(*inI) ; fFile.read(pReadBuf, stBytes) ; dReadTime += RealTime_Microsecs() - dTime ; ++inI ; } } while (--stCopySize) ; std::cout << "Write time is " << xw::str::itoa(dWriteTime, 5, 'f') << " (Ave: " << xw::str::itoa(dWriteTime/stTimes, 10, 'f') << ")" << std::endl ; if ( !bWriteOnly ) { std::cout << "Read time is " << xw::str::itoa(dReadTime, 5, 'f') << " (Ave: " << xw::str::itoa(dReadTime/stTimes, 10, 'f') << ")" << std::endl ; } } // End // Write in order if ( bOrdered ) { std::set<size_t>::iterator i = outSet.begin() ; dWriteTime = 0.0 ; stCopySize = 0 ; for(; i != outSet.end(); ++i) { stPos = *i ; dTime = RealTime_Microsecs() ; fFile.seekp(stPos) ; fFile.write(pPattern, stBytes) ; dWriteTime += RealTime_Microsecs() - dTime ; ++stCopySize ; } std::cout << "Ordered Write time is " << xw::str::itoa(dWriteTime, 5, 'f') << " in " << xw::str::itoa(stCopySize) << " (Ave: " << xw::str::itoa(dWriteTime/stCopySize, 10, 'f') << ")" << std::endl ; if ( !bWriteOnly ) { i = inSet.begin() ; dReadTime = 0.0 ; stCopySize = 0 ; for(; i != inSet.end(); ++i) { stPos = *i ; dTime = RealTime_Microsecs() ; fFile.seekg(stPos) ; fFile.read(pReadBuf, stBytes) ; dReadTime += RealTime_Microsecs() - dTime ; ++stCopySize ; } std::cout << "Ordered Read time is " << xw::str::itoa(dReadTime, 5, 'f') << " in " << xw::str::itoa(stCopySize) << " (Ave: " << xw::str::itoa(dReadTime/stCopySize, 10, 'f') << ")" << std::endl ; } }// End // Write in reverse order if ( bReverse ) { std::set<size_t>::reverse_iterator i = outSet.rbegin() ; dWriteTime = 0.0 ; stCopySize = 0 ; for(; i != outSet.rend(); ++i) { stPos = *i ; dTime = RealTime_Microsecs() ; fFile.seekp(stPos) ; fFile.write(pPattern, stBytes) ; dWriteTime += RealTime_Microsecs() - dTime ; ++stCopySize ; } std::cout << "Reverse ordered Write time is " << xw::str::itoa(dWriteTime, 5, 'f') << " in " << xw::str::itoa(stCopySize) << " (Ave: " << xw::str::itoa(dWriteTime/stCopySize, 10, 'f') << ")" << std::endl ; if ( !bWriteOnly ) { i = inSet.rbegin() ; dReadTime = 0.0 ; stCopySize = 0 ; for(; i != inSet.rend(); ++i) { stPos = *i ; dTime = RealTime_Microsecs() ; fFile.seekg(stPos) ; fFile.read(pReadBuf, stBytes) ; dReadTime += RealTime_Microsecs() - dTime ; ++stCopySize ; } std::cout << "Reverse ordered Read time is " << xw::str::itoa(dReadTime, 5, 'f') << " in " << xw::str::itoa(stCopySize) << " (Ave: " << xw::str::itoa(dReadTime/stCopySize, 10, 'f') << ")" << std::endl ; } }// End dTime = RealTime_Microsecs() ; fFile.close() ; std::cout << "Flush/Close Time is " << xw::str::itoa(RealTime_Microsecs()-dTime, 5, 'f') << std::endl ; std::cout << "Program Terminated" << std::endl ; } catch(...) { std::cout << "Something wrong or wrong parameters" << std::endl ; retval = -1 ; } if ( p ) delete []p ; if ( pPattern ) delete []pPattern ; if ( pReadBuf ) delete []pReadBuf ; return retval ; }

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  • socket connection failed, telnet OK

    - by cf16
    my problem is that I can't connect two comps through socket (windows xp and windows7) although the server created with socket is listening and I can telnet it. It receives then information and does what should be done, but if I run the corresponding socket client I get error 10061. Moreover I am behind firewall - these two comps are running within my LAN, the windows firewalls are turned off, comp1: 192.168.1.2 port 12345 comp1: 192.168.1.6 port 12345 router: 192.168.1.1 Maybe port forwarding could help? But most important for me is to answer why Sockets fail if telnet works fine. client: int main(){ // Initialize Winsock. WSADATA wsaData; int iResult = WSAStartup(MAKEWORD(2,2), &wsaData); if (iResult != NO_ERROR) printf("Client: Error at WSAStartup().\n"); else printf("Client: WSAStartup() is OK.\n"); // Create a socket. SOCKET m_socket; m_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if (m_socket == INVALID_SOCKET){ printf("Client: socket() - Error at socket(): %ld\n", WSAGetLastError()); WSACleanup(); return 7; }else printf("Client: socket() is OK.\n"); // Connect to a server. sockaddr_in clientService; clientService.sin_family = AF_INET; //clientService.sin_addr.s_addr = inet_addr("77.64.240.156"); clientService.sin_addr.s_addr = inet_addr("192.168.1.5"); //clientService.sin_addr.s_addr = inet_addr("87.207.222.5"); clientService.sin_port = htons(12345); if (connect(m_socket, (SOCKADDR*)&clientService, sizeof(clientService)) == SOCKET_ERROR){ printf("Client: connect() - Failed to connect.\n"); wprintf(L"connect function failed with error: %ld\n", WSAGetLastError()); iResult = closesocket(m_socket); if (iResult == SOCKET_ERROR) wprintf(L"closesocket function failed with error: %ld\n", WSAGetLastError()); WSACleanup(); return 6; } // Send and receive data int bytesSent; int bytesRecv = SOCKET_ERROR; // Be careful with the array bound, provide some checking mechanism char sendbuf[200] = "Client: Sending some test string to server..."; char recvbuf[200] = ""; bytesSent = send(m_socket, sendbuf, strlen(sendbuf), 0); printf("Client: send() - Bytes Sent: %ld\n", bytesSent); while(bytesRecv == SOCKET_ERROR){ bytesRecv = recv(m_socket, recvbuf, 32, 0); if (bytesRecv == 0 || bytesRecv == WSAECONNRESET){ printf("Client: Connection Closed.\n"); break; }else printf("Client: recv() is OK.\n"); if (bytesRecv < 0) return 0; else printf("Client: Bytes received - %ld.\n", bytesRecv); } system("pause"); return 0; } server: int main(){ WORD wVersionRequested; WSADATA wsaData={0}; int wsaerr; // Using MAKEWORD macro, Winsock version request 2.2 wVersionRequested = MAKEWORD(2, 2); wsaerr = WSAStartup(wVersionRequested, &wsaData); if (wsaerr != 0){ /* Tell the user that we could not find a usable WinSock DLL.*/ printf("Server: The Winsock dll not found!\n"); return 0; }else{ printf("Server: The Winsock dll found!\n"); printf("Server: The status: %s.\n", wsaData.szSystemStatus); } /* Confirm that the WinSock DLL supports 2.2.*/ /* Note that if the DLL supports versions greater */ /* than 2.2 in addition to 2.2, it will still return */ /* 2.2 in wVersion since that is the version we */ /* requested. */ if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2 ){ /* Tell the user that we could not find a usable WinSock DLL.*/ printf("Server: The dll do not support the Winsock version %u.%u!\n", LOBYTE(wsaData.wVersion), HIBYTE(wsaData.wVersion)); WSACleanup(); return 0; }else{ printf("Server: The dll supports the Winsock version %u.%u!\n", LOBYTE(wsaData.wVersion), HIBYTE(wsaData.wVersion)); printf("Server: The highest version this dll can support: %u.%u\n", LOBYTE(wsaData.wHighVersion), HIBYTE(wsaData.wHighVersion)); } //////////Create a socket//////////////////////// //Create a SOCKET object called m_socket. SOCKET m_socket; // Call the socket function and return its value to the m_socket variable. // For this application, use the Internet address family, streaming sockets, and the TCP/IP protocol. // using AF_INET family, TCP socket type and protocol of the AF_INET - IPv4 m_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); // Check for errors to ensure that the socket is a valid socket. if (m_socket == INVALID_SOCKET){ printf("Server: Error at socket(): %ld\n", WSAGetLastError()); WSACleanup(); //return 0; }else{ printf("Server: socket() is OK!\n"); } ////////////////bind////////////////////////////// // Create a sockaddr_in object and set its values. sockaddr_in service; // AF_INET is the Internet address family. service.sin_family = AF_INET; // "127.0.0.1" is the local IP address to which the socket will be bound. service.sin_addr.s_addr = htons(INADDR_ANY);//inet_addr("127.0.0.1");//htons(INADDR_ANY); //inet_addr("192.168.1.2"); // 55555 is the port number to which the socket will be bound. // using the htons for big-endian service.sin_port = htons(12345); // Call the bind function, passing the created socket and the sockaddr_in structure as parameters. // Check for general errors. if (bind(m_socket, (SOCKADDR*)&service, sizeof(service)) == SOCKET_ERROR){ printf("Server: bind() failed: %ld.\n", WSAGetLastError()); closesocket(m_socket); //return 0; }else{ printf("Server: bind() is OK!\n"); } // Call the listen function, passing the created socket and the maximum number of allowed // connections to accept as parameters. Check for general errors. if (listen(m_socket, 1) == SOCKET_ERROR) printf("Server: listen(): Error listening on socket %ld.\n", WSAGetLastError()); else{ printf("Server: listen() is OK, I'm waiting for connections...\n"); } // Create a temporary SOCKET object called AcceptSocket for accepting connections. SOCKET AcceptSocket; // Create a continuous loop that checks for connections requests. If a connection // request occurs, call the accept function to handle the request. printf("Server: Waiting for a client to connect...\n"); printf("***Hint: Server is ready...run your client program...***\n"); // Do some verification... while (1){ AcceptSocket = SOCKET_ERROR; while (AcceptSocket == SOCKET_ERROR){ AcceptSocket = accept(m_socket, NULL, NULL); } // else, accept the connection... note: now it is wrong implementation !!!!!!!! !! !! (only 1 char) // When the client connection has been accepted, transfer control from the // temporary socket to the original socket and stop checking for new connections. printf("Server: Client Connected! Mammamija. \n"); m_socket = AcceptSocket; char recvBuf[200]=""; char * rc=recvBuf; int bytesRecv=recv(m_socket,recvBuf,64,0); if(bytesRecv==0 || bytesRecv==WSAECONNRESET){ cout<<"server: connection closed.\n"; }else{ cout<<"server: recv() is OK.\n"; if(bytesRecv<0){ return 0; }else{ printf("server: bytes received: %ld.\n",recvBuf); } }

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  • What is the cause of these Visual Studio 2010 errors & warnings?

    - by volpack
    I don't know the cause of these errors I am receiving from Visual Studio 2010. This is the code from my program from line 343 to line 408: int create_den_from_img(char *img_file_name_part, int xlen, int ylen, int zlen ) { IplImage* imgs = 0; char str[80]; unsigned char *data,*imgdata; /* allocating memory */ data = (unsigned char *) malloc(xlen * ylen * zlen * sizeof(unsigned char) ); if(data==NULL) { printf("error in allocating memory \n"); exit(1); } /* Getting the filename & iterating through tiff images */ for(int k = 0; k < zlen; k++) { int count=2; int tmp=k+1; while(tmp/10) { count=count-1; tmp=tmp/10; } switch(count) { case 2:sprintf(str,"%s00%d.tif",img_file_name_part,k+1); break; case 1:sprintf(str,"%s0%d.tif",img_file_name_part,k+1); break; default:sprintf(str,"%s%d.tif",img_file_name_part,k+1); break; } printf("%s\n",str); /* Loading Image using OpenCV */ imgs=cvLoadImage(str,-1); if(imgs==NULL) { printf("error in opening image \n"); exit(1); } imgdata=(uchar *)imgs->imageData; for(int j =0; j < ylen; j++) { for(int i =0; i < xlen; i++) { data[ k*xlen*ylen + j*xlen + i ] = imgdata[ j*xlen+i ]; } } cvReleaseImage(&imgs ); } /* populating `data` variable is done. So, calling `write_den` */ if(write_den("test.den",data,xlen,ylen,zlen)==0) { printf("Error in creating den file\n"); exit(1); } printf("Den file created\n"); } These are the list of errors: Error 3 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 358 1 MTP_TEST Error 4 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 358 1 MTP_TEST Error 5 error C2143: syntax error : missing ')' before 'type' c:\examples\denfile.c 358 1 MTP_TEST Error 6 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 358 1 MTP_TEST Error 7 error C2065: 'k' : undeclared identifier c:\examples\denfile.c 358 1 MTP_TEST Error 9 error C2065: 'k' : undeclared identifier c:\examples\denfile.c 358 1 MTP_TEST Error 10 error C2059: syntax error : ')' c:\examples\denfile.c 358 1 MTP_TEST Error 11 error C2143: syntax error : missing ';' before '{' c:\examples\denfile.c 359 1 MTP_TEST Error 12 error C2065: 'k' : undeclared identifier c:\examples\denfile.c 361 1 MTP_TEST Error 13 error C2065: 'k' : undeclared identifier c:\examples\denfile.c 370 1 MTP_TEST Error 14 error C2065: 'k' : undeclared identifier c:\examples\denfile.c 372 1 MTP_TEST Error 15 error C2065: 'k' : undeclared identifier c:\examples\denfile.c 374 1 MTP_TEST Error 16 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 388 1 MTP_TEST Error 17 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 388 1 MTP_TEST Error 18 error C2143: syntax error : missing ')' before 'type' c:\examples\denfile.c 388 1 MTP_TEST Error 19 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 388 1 MTP_TEST Error 20 error C2065: 'j' : undeclared identifier c:\examples\denfile.c 388 1 MTP_TEST Error 22 error C2065: 'j' : undeclared identifier c:\examples\denfile.c 388 1 MTP_TEST Error 23 error C2059: syntax error : ')' c:\examples\denfile.c 388 1 MTP_TEST Error 24 error C2143: syntax error : missing ';' before '{' c:\examples\denfile.c 389 1 MTP_TEST Error 25 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 390 1 MTP_TEST Error 26 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 390 1 MTP_TEST Error 27 error C2143: syntax error : missing ')' before 'type' c:\examples\denfile.c 390 1 MTP_TEST Error 28 error C2143: syntax error : missing ';' before 'type' c:\examples\denfile.c 390 1 MTP_TEST Error 29 error C2065: 'i' : undeclared identifier c:\examples\denfile.c 390 1 MTP_TEST Error 31 error C2065: 'i' : undeclared identifier c:\examples\denfile.c 390 1 MTP_TEST Error 32 error C2059: syntax error : ')' c:\examples\denfile.c 390 1 MTP_TEST Error 33 error C2143: syntax error : missing ';' before '{' c:\examples\denfile.c 391 1 MTP_TEST Error 34 error C2065: 'k' : undeclared identifier c:\examples\denfile.c 392 1 MTP_TEST Error 35 error C2065: 'j' : undeclared identifier c:\examples\denfile.c 392 1 MTP_TEST Error 36 error C2065: 'i' : undeclared identifier c:\examples\denfile.c 392 1 MTP_TEST Error 37 error C2065: 'j' : undeclared identifier c:\examples\denfile.c 392 1 MTP_TEST Error 38 error C2065: 'i' : undeclared identifier c:\examples\denfile.c 392 1 MTP_TEST I've been getting these kind of errors all day long. Sometimes the code compiles, while at other time it doesn't. Its really annoying.

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  • Communication with HyperTerminal [ QT and WINApi ]

    - by javaAmator
    Hi! I write program to communicate with modem (it useing Hayes commands) and this is working. GUI is programmed with QT, but communication with COM port is write with winapi library. I have problem when I want to send with my program message from one computer to another, i can't send Polish chars (they are repleaced by '?'), how can I fix it ? Does anyone have idea ?? And I have one more problem, I can't send message from my program to Microsoft HyperTerminal, HyperTerminal receive something, but not that what I send. Thx for any help :) Important pieces of code: Connect with port: portHandle = CreateFile (portName, GENERIC_WRITE | GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL); GetCommState (portHandle, &dcb); switch(ui->comboBox->currentIndex()) { case 0 : dcb.BaudRate=CBR_110; break; case 1 : dcb.BaudRate=CBR_300; break; case 2 : dcb.BaudRate=CBR_600; break; case 3 : dcb.BaudRate=CBR_1200; break; case 4 : dcb.BaudRate=CBR_2400; break; case 5 : dcb.BaudRate=CBR_4800; break; case 6 : dcb.BaudRate=CBR_9600; break; case 7 : dcb.BaudRate=CBR_14400; break; case 8 : dcb.BaudRate=CBR_19200; break; case 9 : dcb.BaudRate=CBR_38400; break; case 10 : dcb.BaudRate=CBR_56000; break; case 11 : dcb.BaudRate=CBR_57600; break; case 12 : dcb.BaudRate=CBR_115200; break; case 13 : dcb.BaudRate=CBR_128000; break; case 14 : dcb.BaudRate=CBR_256000; break; } dcb.fBinary = TRUE; dcb.fParity = TRUE; dcb.fOutxCtsFlow = FALSE; dcb.fOutxDsrFlow = FALSE; dcb.fDtrControl = DTR_CONTROL_ENABLE; dcb.fDsrSensitivity = FALSE; dcb.fTXContinueOnXoff = TRUE; dcb.fOutX = FALSE; dcb.fInX = FALSE; dcb.fErrorChar = FALSE; dcb.fNull = FALSE; dcb.fRtsControl = RTS_CONTROL_ENABLE; dcb.fAbortOnError = FALSE; //dcb.ByteSize = dataBits; dcb.DCBlength = sizeof (DCB); switch(ui->comboBox_3->currentIndex()) { case 1 : dcb.Parity = EVENPARITY; break; case 3 : dcb.Parity = MARKPARITY; break; case 2 : dcb.Parity = ODDPARITY; break; case 4 : dcb.Parity = SPACEPARITY; break; case 0 : dcb.Parity = NOPARITY; break; } switch (ui->comboBox_4->currentIndex()) { case 0 : dcb.StopBits = ONESTOPBIT; break; case 1 : dcb.StopBits = ONE5STOPBITS;break; case 2 : dcb.StopBits = TWOSTOPBITS; break; } switch (ui->comboBox_2->currentIndex()) { case 0 : dcb.ByteSize = 5; break; case 1 : dcb.ByteSize = 6;break; case 2 : dcb.ByteSize= 7; break; case 3 : dcb.ByteSize = 8; break; } SetCommState (portHandle, &dcb); GetCommTimeouts (portHandle, &CommTimeouts); CommTimeouts.ReadIntervalTimeout = MAXDWORD; CommTimeouts.ReadTotalTimeoutMultiplier = 0; CommTimeouts.ReadTotalTimeoutConstant = 0; CommTimeouts.WriteTotalTimeoutMultiplier = 10; CommTimeouts.WriteTotalTimeoutConstant = 1000; SetCommTimeouts (portHandle, &CommTimeouts); Send MSG: void MainWindow::Send(char c) { do {WriteFile(portHandle, &c, 1, &cbWritten, NULL); } while (!(cbWritten)); } void MainWindow::on_pushButton_clicked() { QString str = ui->lineEdit->text(); std::string str2; ui->lineEdit->clear(); str2 = str.toStdString(); for(int i=0; i < str2.size();i++) { Send(str2[i]); //qDebug()<< str2[i]; } Send(char(13)); } Receive MSG: void ReaderThread::run() { char c; while(1) { c = Receive(); if(c==13) { emit insertPlainText("\n"); } else { emit insertPlainText(QString(c)); } } } char ReaderThread::Receive() { char c; do{ ReadFile(portHandle, &c, 1, &cbRead, NULL); } while (!(cbRead)); return c; }

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  • flex and bison: wrong output

    - by user2972227
    I am doing a homework using flex and bison to make a complex number calculator. But my program cannot give a correct output. .lex file: %option noyywrap %{ #include<stdio.h> #include<stdlib.h> #include "complex_cal.h" #define YYSTYPE complex #include "complex_cal.tab.h" void RmWs(char* str); %} /* Add your Flex definitions here */ /* Some definitions are already provided to you*/ ws [ \t]+ digits [0-9] number (0|[1-9]+{digits}*)\.?{digits}* im [i] complexnum {ws}*[-]*{ws}*{number}{ws}*[+|-]{ws}*{number}{ws}*{im}{ws}* op [-+*/()] %% {complexnum} {RmWs(yytext); sscanf(yytext,"%lf %lf",&(yylval.real),&(yylval.img)); return CNUMBER;} {ws} /**/ {op} return *yytext; %% /* function provided to student to remove */ /* all the whitespaces from a string. */ void RmWs(char* str){ int i=0,j=0; char temp[strlen(str)+1]; strcpy(temp,str); while (temp[i]!='\0'){ while (temp[i]==' '){i++;} str[j]=temp[i]; i++; j++; } str[j]='\0'; } .y file: %{ #include <stdio.h> #include <stdlib.h> #include "complex_cal.h" /* prototypes of the provided functions */ complex complex_add (complex, complex); complex complex_sub (complex, complex); complex complex_mul (complex, complex); complex complex_div (complex, complex); /* prototypes of the provided functions */ int yylex(void); int yyerror(const char*); %} %token CNUMBER %left '+' '-' %left '*' '/' %nonassoc '(' ')' %% /* start: Add your grammar rules and actions here */ complexexp: complexexp '+' complexexpmultidiv {$$=complex_add($1, $3);} | complexexp '-' complexexpmultidiv {$$=complex_sub($1, $3);} | complexexpmultidiv {$$.real=$1.real;$$.img=$1.img;} ; complexexpmultidiv: complexexpmultidiv '*' complexsimple {$$=complex_mul($1, $3);} | complexexpmultidiv '/' complexsimple {$$=complex_div($1, $3);} | complexsimple {$$.real=$1.real;$$.img=$1.img;} ; complexsimple: '(' complexexp ')' {$$.real=$2.real;$$.img=$2.img;} | '(' CNUMBER ')' {$$.real=$2.real;$$.img=$2.img;} ; /* end: Add your grammar rules and actions here */ %% int main(){ return yyparse(); } int yyerror(const char* s){ printf("%s\n", s); return 0; } /* function provided to do complex addition */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of addition in c3 */ complex complex_add (complex c1, complex c2){ /* c1 + c2 */ complex c3; c3.real = c1.real + c2.real; c3.img = c1.img + c2.img; return c3; } /* function provided to do complex subtraction */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of subtraction in c3 */ complex complex_sub (complex c1, complex c2){ /* c1 - c2 */ complex c3; c3.real = c1.real - c2.real; c3.img = c1.img - c2.img; return c3; } /* function provided to do complex multiplication */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of multiplication in c3 */ complex complex_mul (complex c1, complex c2){ /* c1 * c2 */ complex c3; c3.real = c1.real*c2.real - c1.img*c2.img; c3.img = c1.img*c2.real + c1.real*c2.img; return c3; } /* function provided to do complex division */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of c1/c2 in c3 */ complex complex_div (complex c1, complex c2){ /* c1 / c2 (i.e. c1 divided by c2 ) */ complex c3; double d; /*divisor calculation using the conjugate of c2*/ d = c2.real*c2.real + c2.img*c2.img; c3.real = (c1.real*c2.real + c1.img*c2.img)/d; c3.img = (c1.img*c2.real - c1.real*c2.img)/d; return c3; } .h file: #include <string.h> /* struct for holding a complex number */ typedef struct { double real; double img; } complex; /* define the return type of FLEX */ #define YYSTYPE complex Script for compiling the file: bison -d -v complex_cal.y flex -ocomplex_cal.lex.yy.c complex_cal.lex gcc -o complex_cal complex_cal.lex.yy.c complex_cal.tab.c ./complex_cal Some correct sample run of the program: input:(5+6i)*(6+1i) output:24.000000+41.000000i input:(7+8i)/(-3-4i)*(5+7i) output:-11.720000-14.040000i input:(7+8i)/((-3-4i)*(5+7i)) output:-0.128108+0.211351i But when I run this program, the program only give an output which is identical to my input. For example, when I input (5+6i)(6+1i), it just gives (5+6i)(6+1i). Even if I input any other things, for example, input "abc" it just gives "abc" and is not syntax error. I don't know where the problem is and I hope to know how to solve it.

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