Search Results

Search found 3255 results on 131 pages for 'pointers'.

Page 19/131 | < Previous Page | 15 16 17 18 19 20 21 22 23 24 25 26  | Next Page >

• CComPtr CoCreateInstance returns 0x80070582 (Class already exists.)

  - by Trevor Balcom

  I have a StartComObjects function called when the user presses the Login button and a StopComObjects function called when the user presses the Cancel button. The StartComObjects function uses CComPtr.CoCreateInstance to create the COM object and sets up some connection points using AfxConnectionAdvise. When the user presses the Cancel button the connection points are disconnected using AfxConnectionUnadvise and the COM object is stopped before calling Release on the CComPtr. When I press the login button a second time the CComPtr.CoCreateInstance returns 0x80070582 (Class already exists). This prevents the COM object from being created on the second call to StartComObjects. I am not sure why this isn't working. Shouldn't CComPtr::Release free the COM object and allow me to create a new one after the old one was stopped? Is there any way to get around this?

  Read the article

• Is this a memory leak?

  - by Ben

  char *pointer1; char *pointer2; pointer1 = new char[256]; pointer2 = pointer1; delete [] pointer1; In other words, do I have to do delete [] pointer2 as well? Thanks!

  Read the article

• How to include only BOOST smart pointer codes into a project?

  - by afriza

  What are best practices to include boost smart pointer library only without adding all boost libraries into the project? I only want boost smart pointer library in my project and I don't want to check in/commit 200 MB source codes (boost 1.42.0) into my project repository just for that. What more, my windows mobile project itself doesn't even reach 10% of that size!

  Read the article

• char *p="orkut" vs const char *p="orkut"

  - by piemesons

  char *p="orkut" vs const char *p="orkut" whats the difference btwn these two...

  Read the article

• memcpy segmentation fault on linux but not os x

  - by Andre

  I'm working on implementing a log based file system for a file as a class project. I have a good amount of it working on my 64 bit OS X laptop, but when I try to run the code on the CS department's 32 bit linux machines, I get a seg fault. The API we're given allows writing DISK_SECTOR_SIZE (512) bytes at a time. Our log record consists of the 512 bytes the user wants to write as well as some metadata (which sector he wants to write to, the type of operation, etc). All in all, the size of the "record" object is 528 bytes, which means each log record spans 2 sectors on the disk. The first record writes 0-512 on sector 0, and 0-15 on sector 1. The second record writes 16-512 on sector 1, and 0-31 on sector 2. The third record writes 32-512 on sector 2, and 0-47 on sector 3. ETC. So what I do is read the two sectors I'll be modifying into 2 freshly allocated buffers, copy starting at record into buf1+the calculated offset for 512-offset bytes. This works correctly on both machines. However, the second memcpy fails. Specifically, "record+DISK_SECTOR_SIZE-offset" in the below code segfaults, but only on the linux machine. Running some random tests, it gets more curious. The linux machine reports sizeof(Record) to be 528. Therefore, if I tried to memcpy from record+500 into buf for 1 byte, it shouldn't have a problem. In fact, the biggest offset I can get from record is 254. That is, memcpy(buf1, record+254, 1) works, but memcpy(buf1, record+255, 1) segfaults. Does anyone know what I'm missing? Record *record = malloc(sizeof(Record)); record->tid = tid; record->opType = OP_WRITE; record->opArg = sector; int i; for (i = 0; i < DISK_SECTOR_SIZE; i++) { record->data[i] = buf[i]; // *buf is passed into this function } char* buf1 = malloc(DISK_SECTOR_SIZE); char* buf2 = malloc(DISK_SECTOR_SIZE); d_read(ad->disk, ad->curLogSector, buf1); d_read(ad->disk, ad->curLogSector+1, buf2); memcpy(buf1+offset, record, DISK_SECTOR_SIZE-offset); memcpy(buf2, record+DISK_SECTOR_SIZE-offset, offset+sizeof(Record)-sizeof(record->data));

  Read the article

• why weak_ptr can break cyclic reference?

  - by skydoor

  I learnt a lot about weak_ptr working with share_ptr to break cyclic reference. How does it work? How to use that? Can any body give me an example? I am totally lost here. One more question, what's a strong pointer?

  Read the article

• Can i pass auto_ptr by reference to functions?

  - by eriks

  is the following function OK: void DoSomething(auto_ptr<int>& a)....

  Read the article

• Converting UnicodeString to PAnsiChar in Delphi XE

  - by moodforaday

  In Delphi XE I am using the BASS audio library, which contains this function: function BASS_StreamCreateURL(url: PAnsiChar; offset: DWORD; flags: DWORD; proc: DOWNLOADPROC; user: Pointer):HSTREAM; stdcall; external bassdll; The 'url' parameter is of type PAnsiChar, so in my code I do a cast: FStreamHandle := BASS_StreamCreateURL(PAnsiChar( url ) [...] The compiler emits a warning on this line: "suspicious typecast of string to PAnsiChar". In trying to eliminate the warning, I found that the recommended way is to use a double cast: FStreamHandle := BASS_StreamCreateURL(PAnsiChar( AnsiString( url )) [...] This does eliminate the warning, but the BASS function now returns error code 2 ("cannot open file"), which tells me the URL string it receives is somehow broken. I cannot see what the bass DLL actually receives, but using a breakpoint in the debugger the string looks good: var s : PAnsiChar; begin s := PAnsiChar( AnsiString( url )); At this point string s appears fine, but the BASS function fails when I pass it. My initial code: PAnsiChar( url ) works well with BASS, but emits a warning. So what's the correct way of getting from UnicodeString to PAnsiChar without a warning?

  Read the article

• How to make the tokenizer detect empty spaces while using strtok()

  - by Shadi Al Mahallawy

  I am designing a c++ program, somewhere in the program i need to detect if there is a blank(empty token) next to the token used know eg. if(token1==start) { token2=strtok(NULL," "); if(token2==NULL) {LCCTR=0;} else {LCCTR=atoi(token2);} so in the previous peice token1 is pointing to start , and i want to check if there is anumber next to the start , so I used token2=strtok(NULL," ") to point to the next token but unfortunattly the strtok function cannot detect empty spaces so it gives me an error at run time"INVALID NULL POINTER" how can i fix it or is there another function to use to detect empty spaces #include <iostream> #include<string> #include<map> #include<iomanip> #include<fstream> #include<ctype.h> using namespace std; const int MAX=300; int LCCTR; int START(char* token1); char* PASS1(char*token1); void tokinizer() { ifstream in; ofstream out; char oneline[MAX]; in.open("infile.txt"); out.open("outfile.txt"); if(in.is_open()) { char *token1; in.getline(oneline,MAX); token1 = strtok(oneline," \t"); START (token1); //cout<<'\t'; while(token1!=NULL) { //PASS1(token1); //cout<<token1<<" "; token1=strtok(NULL," \t"); if(NULL==token1) {//cout<<endl; //cout<<LCCTR<<'\t'; in.getline(oneline,MAX); token1 = strtok(oneline," \t"); } } } in.close(); out.close(); } int START(char* token1) { string start("START"); char*token2; if(token1 != start) {LCCTR=0;} else if(token1==start) { token2=strchr(token1+2,' '); cout<<token2; if(token2==NULL) {LCCTR=0;} else {LCCTR=atoi(token2); if(atoi(token2)>9999||atoi(token2)<0){cout<<"IVALID STARTING ADDRESS"<<endl;exit(1);} } } return LCCTR; } char* PASS1 (char*token1) { map<string,int> operations; map<string,int>symtable; map<string,int>::iterator it; pair<map<string,int>::iterator,bool> ret; char*token3=NULL; char*token2=NULL; string test; string comp(" "); string start("START"); string word("WORD"); string byte("BYTE"); string resb("RESB"); string resw("RESW"); string end("END"); operations["ADD"] = 18; operations["AND"] = 40; operations["COMP"] = 28; operations["DIV"] = 24; operations["J"] = 0X3c; operations["JEQ"] =30; operations["JGT"] =34; operations["JLT"] =38; operations["JSUB"] =48; operations["LDA"] =00; operations["LDCH"] =50; operations["LDL"] =55; operations["LDX"] =04; operations["MUL"] =20; operations["OR"] =44; operations["RD"] =0xd8; operations["RSUB"] =0x4c; operations["STA"] =0x0c; operations["STCH"] =54; operations["STL"] =14; operations["STSW"] =0xe8; operations["STX"] =10; operations["SUB"] =0x1c; operations["TD"] =0xe0; operations["TIX"] =0x2c; operations["WD"] =0xdc; if(operations.find("ADD")->first==token1) { token2=strtok(NULL," "); //test=token2; cout<<token2; //if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} //else{LCCTR=LCCTR+3;} } /*else if(operations.find("AND")->first==token1) { token2=strtok(NULL," "); test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("COMP")->first==token1) { token2=token1+5; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("DIV")->first==token1) { token2=token1+4; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("J")->first==token1) { token2=token1+2; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("JEQ")->first==token1) { token2=token1+5; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("JGT")->first==token1) { token2=strtok(NULL," "); test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("JLT")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("JSUB")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("LDA")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("LDCH")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("LDL")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("LDX")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("MUL")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("OR")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("RD")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("RSUB")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("STA")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("STCH")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("STL")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("STSW")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("STX")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("SUB")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("TD")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("TIX")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} } else if(operations.find("WD")->first==token1) { token2=token1+6; test=token2; if(test.empty()){cout<<"MISSING OPERAND"<<endl;exit(1);} else{LCCTR=LCCTR+3;} }*/ //else if( if(word==token1) {LCCTR=LCCTR+3;} else if(byte==token1) {string test; token2=token1+7; test=token2; if(test[0]=='C') {token3=token1+10; test=token3; if(test.length()>15) {cout<<"ERROR"<<endl; exit(1);} } else if(test[0]=='X') {token3=token1+10; test=token3; if(test.length()>14) {cout<<"ERROR"<<endl; exit(1);} } LCCTR=LCCTR+test.length(); } else if(resb==token1) {token3=token1+5; LCCTR=LCCTR+atoi(token3);} else if(resw==token1) {token3=token1+5; LCCTR=LCCTR+3*atoi(token3);} else if(end==token1) {exit(1);} /*else { test=token1; int last=test.length(); if(token1==start||test[0]=='C'||test[0]=='X'||ispunct(test[last])||isdigit(test[0])||isdigit(test[1])||isdigit(test[2])||isdigit(test[3])){} else { token2=strtok(NULL," "); //test=token2; cout<<token2; if(token2!=NULL) { symtable.insert( pair<string,int>(token1,LCCTR)); for(it=symtable.begin() ;it!=symtable.end() ;++it) {/*cout<<"symbol: "<<it->first<<" LCCTR: "<<it->second<<endl;} } else{} } }*/ return token3; } int main() { tokinizer(); return 0; }

  Read the article

• should std::auto_ptr<>::operator = reset / deallocate its existing pointee ?

  - by afriza

  I read here about std::auto_ptr<::operator= Notice however that the left-hand side object is not automatically deallocated when it already points to some object. You can explicitly do this by calling member function reset before assigning it a new value. However, when I read the source code for header file C:\Program Files\Microsoft Visual Studio 8\VC\ce\include\memory template<class _Other> auto_ptr<_Ty>& operator=(auto_ptr<_Other>& _Right) _THROW0() { // assign compatible _Right (assume pointer) reset(_Right.release()); return (*this); } auto_ptr<_Ty>& operator=(auto_ptr<_Ty>& _Right) _THROW0() { // assign compatible _Right (assume pointer) reset(_Right.release()); return (*this); } auto_ptr<_Ty>& operator=(auto_ptr_ref<_Ty> _Right) _THROW0() { // assign compatible _Right._Ref (assume pointer) _Ty **_Pptr = (_Ty **)_Right._Ref; _Ty *_Ptr = *_Pptr; *_Pptr = 0; // release old reset(_Ptr); // set new return (*this); } What is the correct/standard behavior? How do other STL implementations behave?

  Read the article

• Bit shift and pointer oddities in C, looking for explanations

  - by foo

  Hi all, I discovered something odd that I can't explain. If someone here can see what or why this is happening I'd like to know. What I'm doing is taking an unsigned short containing 12 bits aligned high like this: 1111 1111 1111 0000 I then want to shif the bits so that each byte in the short hold 7bits with the MSB as a pad. The result on what's presented above should look like this: 0111 1111 0111 1100 What I have done is this: unsigned short buf = 0xfff; //align high buf <<= 4; buf >>= 1; *((char*)&buf) >>= 1; This gives me something like looks like it's correct but the result of the last shift leaves the bit set like this: 0111 1111 1111 1100 Very odd. If I use an unsigned char as a temporary storage and shift that then it works, like this: unsigned short buf = 0xfff; buf <<= 4; buf >>= 1; tmp = *((char*)&buf); *((char*)&buf) = tmp >> 1; The result of this is: 0111 1111 0111 1100 Any ideas what is going on here?

  Read the article

• How to do pointer work with accessor methods in Objective-C

  - by Jasconius

  Basic problem statement: I have a very good reason for doing some pointer fanciness in an app where I need to pass a decimal by reference. So I have a class which stores many a decimal, so let's say is has a property as such: @property (nonatomic) double myDecimalValue; I want to pass it by reference to some other class. [someOtherObject sendMyDecimalByReference:&myDecimalValue]; But, a problem emerges! The way that actually has to be written (because it's a property) is [someOtherObject sendMyDecimalByReference:&decimalOrigin.myDecimalValue]; This fails to compile in objective-c I get around it by writing the following - (double *) myDecimalValueRef; [someOtherObject sendMyDecimalByReference:[decimalOrigin myDecimalValue]]; Except I have dozens of these decimals and I don't want to write that stupid wrapper function for every value. Is there a shorthand way to do this in Objective-C using just the Getter functions? Let's just assume I have a great reason for not using NSNumber. Thanks!

  Read the article

• convert pointer to pointer to void pointer

  - by FihopZz

  When I'm learning to use qsort to sort an array of string, there is a question puzzled me. For example, to sort the following s char *s[] = { "Amit", "Garima", "Gaurav", "Vaibhav" }; To use the qsort, you must provide a comparison function like the following function cstring_cmp I guess in the qsort function, the type of parameter to be passed to the function cstring_cmp is char**. How to convert a char** to a void*? Why can we convert a char** to a void*? int cstring_cmp(const void *a, const void *b) { const char **ia = (const char **)a; const char **ib = (const char **)b; return -strcasecmp(*ia, *ib); /* return the negative of the normal comparison */ }

  Read the article

• A queue in C using structs and dynamic memory allocation (linked list)

  - by Martin Pugh

  I am tasked with making a queue data structure in C, as a linked list. Our lecturer gave us a large amount of code to implement a stack, but we have to adapt it to create a queue. The code our lecturer gave us ends up not compiling and segfaulting at the exact same point as the code I wrote for the queue. I'm very new to structs, malloc and C in general, so there could be something painfully obvious I've overlooked. Here is the code I am using: #include <stdio.h> #include <stdlib.h> struct node{ int data; //contains the actual data struct node *prev; //pointer to previous node (Closer to front) struct node *next; //pointer to next node (Closer to back) }; typedef struct node *Nodepointer; struct queue{ Nodepointer front; Nodepointer back; }; typedef struct queue *Queuepointer; main(){ Queuepointer myqueue; //create a queue called myqueue init(myqueue); //initialise the queue Nodepointer new = (Nodepointer)malloc(sizeof(struct node)); myqueue->front = new; } int init(Queuepointer q){ q = (Queuepointer)malloc(sizeof(struct queue)); q->front = NULL; q->back = NULL; } The idea is that the queue struct 'contains' the first and last nodes in a queue, and when a node is created, myqueue is updated. However, I cannot even get to that part (pop and push are written but omitted for brevity). The code is segfaulting at the line myqueue->front = new; with the following gdb output: Program received signal SIGSEGV, Segmentation fault. 0x08048401 in main () at queue.c:27 27 myqueue->front = new; Any idea what I'm doing wrong?

  Read the article

• casting void* to float* creates only zeros

  - by Paperflyer

  I am reading an audio file using CoreAudio (Extended Audio File Read Services). The audio data gets converted to 4-byte float and handed to me as a void* buffer. It can be played with Audio Queue Services, so its content is correct. Next, I want to draw a waveform and thus need access to the actual samples. So, I cast void* audioData to float*: Float32 *floatData = (Float32 *)audioData; When accessing this data however, I only get 0.0 regardless of the index. Float32 value = floatData[index]; // Is always zero for any index Am I doing something wrong with the cast?

  Read the article

• Function lfit in numerical recipes, providing a test function

  - by Simon Walker

  Hi I am trying to fit collected data to a polynomial equation and I found the lfit function from Numerical Recipes. I only have access to the second edition, so am using that. I have read about the lfit function and its parameters, one of which is a function pointer, given in the documentation as void (*funcs)(float, float [], int)) with the help The user supplies a routine funcs(x,afunc,ma) that returns the ma basis functions evaluated at x = x in the array afunc[1..ma]. I am struggling to understand how this lfit function works. An example function I found is given below: void fpoly(float x, float p[], int np) /*Fitting routine for a polynomial of degree np-1, with coe?cients in the array p[1..np].*/ { int j; p[1]=1.0; for (j=2;j<=np;j++) p[j]=p[j-1]*x; } When I run through the source code for the lfit function in gdb I can see no reference to the funcs pointer. When I try and fit a simple data set with the function, I get the following error message. Numerical Recipes run-time error... gaussj: Singular Matrix ...now exiting to system... Clearly somehow a matrix is getting defined with all zeroes. I am going to involve this function fitting in a large loop so using another language is not really an option. Hence why I am planning on using C/C++. For reference, the test program is given here: int main() { float x[5] = {0., 0., 1., 2., 3.}; float y[5] = {0., 0., 1.2, 3.9, 7.5}; float sig[5] = {1., 1., 1., 1., 1.}; int ndat = 4; int ma = 4; /* parameters in equation */ float a[5] = {1, 1, 1, 0.1, 1.5}; int ia[5] = {1, 1, 1, 1, 1}; float **covar = matrix(1, ma, 1, ma); float chisq = 0; lfit(x,y,sig,ndat,a,ia,ma,covar,&chisq,fpoly); printf("%f\n", chisq); free_matrix(covar, 1, ma, 1, ma); return 0; } Also confusing the issue, all the Numerical Recipes functions are 1 array-indexed so if anyone has corrections to my array declarations let me know also! Cheers

  Read the article

• C++ -- Is there an implicit cast here from Fred* to auto_ptr<Fred>?

  - by q0987

  Hello all, I saw the following code, #include <new> #include <memory> using namespace std; class Fred; // Forward declaration typedef auto_ptr<Fred> FredPtr; class Fred { public: static FredPtr create(int i) { return new Fred(i); // Is there an implicit casting here? If not, how can we return // a Fred* with return value as FredPtr? } private: Fred(int i=10) : i_(i) { } Fred(const Fred& x) : i_(x.i_) { } int i_; }; Please see the question listed in function create. Thank you // Updated based on comments Yes, the code cannot pass the VC8.0 error C2664: 'std::auto_ptr<_Ty::auto_ptr(std::auto_ptr<_Ty &) throw()' : cannot convert parameter 1 from 'Fred *' to 'std::auto_ptr<_Ty &' The code was copied from the C++ FAQ 12.15. However, after making the following changes, replace return new Fred(i); with return auto_ptr<Fred>(new Fred(i)); This code can pass the VC8.0 compiler. But I am not sure whether or not this is a correct fix.

  Read the article

• Problem with memset after an instance of a user defined class is created and a file is opened

  - by Liberalkid

  I'm having a weird problem with memset, that was something to do with a class I'm creating before it and a file I'm opening in the constructor. The class I'm working with normally reads in an array and transforms it into another array, but that's not important. The class I'm working with is: #include <vector> #include <algorithm> using namespace std; class PreProcess { public: PreProcess(char* fileName,char* outFileName); void SortedOrder(); private: vector< vector<double > > matrix; void SortRow(vector<double> &row); char* newFileName; vector< pair<double,int> > rowSorted; }; The other functions aren't important, because I've stopped calling them and the problem persists. Essentially I've narrowed it down to my constructor: PreProcess::PreProcess(char* fileName,char* outFileName):newFileName(outFileName){ ifstream input(fileName); input.close(); //this statement is inconsequential } I also read in the file in my constructor, but I've found that the problem persists if I don't read in the matrix and just open the file. Essentially I've narrowed it down to if I comment out those two lines the memset works properly, otherwise it doesn't. Now to the context of the problem I'm having with it: I wrote my own simple wrapper class for matrices. It doesn't have much functionality, I just need 2D arrays in the next part of my project and having a class handle everything makes more sense to me. The header file: #include <iostream> using namespace std; class Matrix{ public: Matrix(int r,int c); int &operator()(int i,int j) {//I know I should check my bounds here return matrix[i*columns+j]; } ~Matrix(); const void Display(); private: int *matrix; const int rows; const int columns; }; Driver: #include "Matrix.h" #include <string> using namespace std; Matrix::Matrix(int r,int c):rows(r),columns(c) { matrix=new int[rows*columns]; memset(matrix,0,sizeof(matrix)); } const void Matrix::Display(){ for(int i=0;i<rows;i++){ for(int j=0;j<columns;j++) cout << (*this)(i,j) << " "; cout << endl; } } Matrix::~Matrix() { delete matrix; } My main program runs: PreProcess test1(argv[1],argv[2]); //test1.SortedOrder(); Matrix test(10,10); test.Display(); And when I run this with the input line uncommented I get: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1371727776 32698 -1 0 0 0 0 0 6332656 0 -1 -1 0 0 6332672 0 0 0 0 0 0 0 0 0 0 0 0 0 -1371732704 32698 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 I really don't have a clue what's going on in memory to cause this, on a side note if I replace memset with: for(int i=0;i<rows*columns;i++) *(matrix+i) &= 0x0; Then it works perfectly, it also works if I don't open the file. If it helps I'm running GCC 64-bit version 4.2.4 on Ubuntu.I assume there's some functionality of memset that I'm not properly understanding.

  Read the article

• Cannot take the address of, get the size of, or declare a pointer to a managed type ('type name')

  - by Behrooz

  this error stops compiling if i have one or more System.String in my structs is there any other way to store strings? i have tried things like this: private long _B_ID; private byte[] _C_Name; private byte[] _C_Address; private byte[] _C_Telephone; but it is not seeming to work.

  Read the article

• Getting the start address of the current process's heap?

  - by beta

  Hey, I am exploring the lower level workings of the system, and was wondering how malloc determines the start address of the heap. Is the heap a constant offset or is there a call of some sort to get the start address? Does the stack effect the start address of the heap? Thanks, Braden McDorman

  Read the article

• Converting a pointer for a base class into an inherited class

  - by Shawn B

  Hey, I'm working on a small roguelike game, and for any object/"thing" that is not a part of the map is based off an XEntity class. There are several classes that depend on it, such as XPlayer, XItem, and XMonster. My problem is, that I want to convert a pointer from XEntity to XItem when I know that an object is in item. The sample code I am using to pick up an item is this, it is when a different entity picks up an item it is standing over. void XEntity::PickupItem() { XEntity *Ent = MapList; // Start of a linked list while(true) { if(Ent == NULL) { break; } if(Ent->Flags & ENT_ITEM) { Ent->RemoveEntity(); // Unlink from the map's linked list XItem *Item = Ent // Problem is here, type-safety // Code to link into inventory is here break; } Ent = Ent->MapList; } } My first thought was to create a method in XEntity that returns itself as an XItem pointer, but it creates circular dependencies that are unresolvable. I'm pretty stumped about this one. Any help is greatly appreciated.

  Read the article

• Pointer initialization doubt

  - by Jestin Joy

  We could initialize a character pointer like this in C. char *c="test"; Where c points to the first character(t). But when I gave code like below. It gives segmentation fault. #include<stdio.h> #include<stdlib.h> main() { int *i=0; printf("%d",*i); } Also when I give #include<stdio.h> #include<stdlib.h> main() { int *i; i=(int *)malloc(2); printf("%d",*i); } It worked(gave output 0). When I gave malloc(0), it worked(gave output 0). Please tell what is happening

  Read the article

• What's correct way to remove a boost::shared_ptr from a list?

  - by Catskul

  I have a std::list of boost::shared_ptr<T> and I want to remove an item from it but I only have a pointer of type T* which matches one of the items in the list. However I cant use myList.remove( tPtr ) I'm guessing because shared_ptr does not implement == for its template argument type. My immediate thought was to try myList.remove( shared_ptr<T>(tPtr) ) which is syntactically correct but it will crash from a double delete since the temporary shared_ptr has a separate use_count. std::list< boost::shared_ptr<T> > myList; T* tThisPtr = new T(); // This is wrong; only done for example code. // stand-in for actual code in T using // T's actual "this" pointer from within T { boost::shared_ptr<T> toAdd( tThisPtr ); // typically would be new T() myList.push_back( toAdd ); } { //T has pointer to myList so that upon a certain action, // it will remove itself romt the list //myList.remove( tThisPtr); //doesn't compile myList.remove( boost::shared_ptr<T>(tThisPtr) ); // compiles, but causes // double delete } The only options I see remaining are to use std::find with a custom compare, or to loop through the list brute force and find it myself, but it seems there should be a better way. Am I missing something obvious, or is this just too non-standard a use to be doing a remove the clean/normal way?

  Read the article

• What are potential dangers when using boost::shared_ptr?

  - by dehmann

  What are some ways you can shoot yourself in the foot when using boost::shared_ptr? In other words, what pitfalls do I have to avoid when I use boost::shared_ptr?

  Read the article

• Deleting a non-owned dynamic array through a pointer

  - by ayanzo

  Hello all, I'm relatively novice when it comes to C++ as I was weened on Java for much of my undergraduate curriculum (tis a shame). Memory management has been a hassle, but I've purchased a number books on ansi C and C++. I've poked around the related questions, but couldn't find one that matched this particular criteria. Maybe it's so obvious nobody mentions it? This question has been bugging me, but I feel as if there's a conceptual point i'm not utilizing. Suppose: char original[56]; cstr[0] = 'a'; cstr[1] = 'b'; cstr[2] = 'c'; cstr[3] = 'd'; cstr[4] = 'e'; cstr[5] = '\0'; char *shaved = shavecstr(cstr); delete[] cstrn; where char* shavecstr(char* cstr) { size_t len = strlen(cstr); char* ncstr = new char[len]; strcpy(ncstr,cstr); return ncstr; } In that the whole point is to have 'original' be a buffer that fills with characters and routinely has its copy shaved and used elsewhere. To prevent leaks, I want to free up the memory held by 'shaved' to be used again after it passes through some arguments. There is probably a good reason for why this is restricted, but there should be some way to free the memory as by this configuration, there is no way to access the original owner (pointer) of the data.

  Read the article

< Previous Page | 15 16 17 18 19 20 21 22 23 24 25 26  | Next Page >