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  • Implementing Operator Overloading with Logarithms in C++

    - by Jacob Relkin
    Hello my friends, I'm having some issues with implementing a logarithm class with operator overloading in C++. My first goal is how I would implement the changeBase method, I've been having a tough time wrapping my head around it. My secoond goal is to be able to perform an operation where the left operand is a double and the right operand is a logarithm object. Here's a snippet of my log class: // coefficient: double // base: unsigned int // number: double class _log { double coefficient, number; unsigned int base; public: _log() { base = rand(); coefficient = rand(); number = rand(); } _log operator+ ( const double b ) const; _log operator* ( const double b ) const; _log operator- ( const double b ) const; _log operator/ ( const double b ) const; _log operator<< ( const _log &b ); double getValue() const; bool changeBase( unsigned int base ); }; You guys are awesome, thank you for your time.

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  • Mysql - Help me alter this search query to get desired results

    - by sandeepan-nath
    Following is a dump of the tables and data needed to answer understand the system:- The system consists of tutors and classes. The data in the table All_Tag_Relations stores tag relations for each tutor registered and each class created by a tutor. The tag relations are used for searching classes. CREATE TABLE IF NOT EXISTS `Tags` ( `id_tag` int(10) unsigned NOT NULL auto_increment, `tag` varchar(255) default NULL, PRIMARY KEY (`id_tag`), UNIQUE KEY `tag` (`tag`), KEY `id_tag` (`id_tag`), KEY `tag_2` (`tag`), KEY `tag_3` (`tag`), KEY `tag_4` (`tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `Tags` (`id_tag`, `tag`) VALUES (1, 'Sandeepan'), (2, 'Nath'), (3, 'first'), (4, 'class'), (5, 'new'), (6, 'Bob'), (7, 'Cratchit'); CREATE TABLE IF NOT EXISTS `All_Tag_Relations` ( `id_tag` int(10) unsigned NOT NULL default '0', `id_tutor` int(10) default NULL, `id_wc` int(10) unsigned default NULL, KEY `All_Tag_Relations_FKIndex1` (`id_tag`), KEY `id_wc` (`id_wc`), KEY `id_tag` (`id_tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `All_Tag_Relations` (`id_tag`, `id_tutor`, `id_wc`) VALUES (1, 1, NULL), (2, 1, NULL), (3, 1, 1), (4, 1, 1), (6, 2, NULL), (7, 2, NULL), (5, 2, 2), (4, 2, 2); Following is my query:- This query searches for "first class" (tag for first = 3 and for class = 4, in Tags table) and returns all those classes such that both the terms first and class are present in the class name. SELECT wtagrels.id_wc,SUM(DISTINCT( wtagrels.id_tag =3)) AS key_1_total_matches, SUM(DISTINCT( wtagrels.id_tag =4)) AS key_2_total_matches FROM all_tag_relations AS wtagrels WHERE ( wtagrels.id_tag =3 OR wtagrels.id_tag =4 ) GROUP BY wtagrels.id_wc HAVING key_1_total_matches = 1 AND key_2_total_matches = 1 LIMIT 0, 20 And it returns the class with id_wc = 1. But, I want the search to show all those classes such that all the search terms are present in the class name or its tutor name So that searching "Sandeepan class" (wtagrels.id_tag = 1,4) or "Sandeepan Nath" also returns the class with id_wc=1. And Searching. Searching "Bob First" should not return any classes. Please modify the above query or suggest a new query, if possible using MyIsam - fulltext search, but somehow help me get the result.

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  • Why does setting this member in C fail?

    - by Lee Crabtree
    I'm writing a Python wrapper for a C++ library, and I'm getting a really weird when trying to set a struct's field in C. If I have a struct like this: struct Thing { PyOBJECT_HEAD unsigned int val; }; And have two functions like this: static PyObject* Thing_GetBit(Thing* self, PyObject* args) { unsigned int mask; if(!PyArg_ParseTuple(args, "I", &mask) Py_RETURN_FALSE; if((self->val & mask) != 0) Py_RETURN_TRUE; Py_RETURN_FALSE; } static PyObject* Thing_SetBit(Thing* self, PyObject* args) { unsigned int mask; bool on; if(!PyArg_ParseTuple(args, "Ii", &mask, &on)) Py_RETURN_FALSE; if(on) thing->val |= mask; else thing->val &= ~mask; Py_RETURN_TRUE; } Python code that calls the first method works just fine, giving back the value of the struct member. Calls to the SetBit method give an error about an object at address foo accessing memory at address bar, which couldn't be "written". I've poked around the code, and it's like I can look at the value all I want, both from C and Python, but the instant I try to set it, it blows up in my face. Am I missing something fundamental here?

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  • sql foreign keys

    - by Paul Est
    I was create tables with the syntax in phpmyadmin: DROP TABLE IF EXISTS users; DROP TABLE IF EXISTS info; CREATE TABLE users ( user_id int unsigned NOT NULL auto_increment, email varchar(100) NOT NULL default '', pwd varchar(32) NOT NULL default '', isAdmin int(1) unsigned NOT NULL, PRIMARY KEY (user_id) ) TYPE=INNODB; CREATE TABLE info ( info_id int unsigned NOT NULL auto_increment, first_name varchar(100) NOT NULL default '', last_name varchar(100) NOT NULL default '', address varchar(300) NOT NULL default '', zipcode varchar(100) NOT NULL default '', personal_phone varchar(100) NOT NULL default '', mobilephone varchar(100) NOT NULL default '', faxe varchar(100) NOT NULL default '', email2 varchar(100) NOT NULL default '', country varchar(100) NOT NULL default '', sex varchar(1) NOT NULL default '', birth varchar(1) NOT NULL default '', email varchar(100) NOT NULL default '', PRIMARY KEY (info_id), FOREIGN KEY (email) REFERENCES users(email) ON UPDATE CASCADE ON DELETE CASCADE ) TYPE=INNODB; But shows the error "#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'TYPE=INNODB' at line 11 " If i remove the TYPE=INNODB in the end of create the tables, it will show the error "#1005 - Can't create table 'curriculo.info' (errno: 150) ".

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  • ldap_bind_s returning LDAP_SUCCESS with wrong credentials

    - by rezna
    Hi guys, I have this little problem. I want to authenticate user against LDAP (Windows Active Directory), everything works OK, but the combination (good user, good password, wrong domain). LDAP* ldap = ldap_init(L"myserver", 389); ULONG ldap_version = 3; ULONG ret = LDAP_SUCCESS; ret = ldap_set_option(ldap, LDAP_OPT_PROTOCOL_VERSION, (void*)&ldap_version); ret = ldap_connect(ldap, NULL); SEC_WINNT_AUTH_IDENTITY ai; ai.Domain = (unsigned short*)BAD_DOMAIN; ai.DomainLength = wcslen(BAD_DOMAIN); ai.User = (unsigned short*)OK_USER; ai.UserLength = wcslen(OK_USER); ai.Password = (unsigned short*)OK_PASS; ai.PasswordLength = wcslen(OK_PASS); ai.Flags = SEC_WINNT_AUTH_IDENTITY_UNICODE; ret = ldap_bind_s(ldap, NULL, (PWCHAR) &ai, LDAP_AUTH_NTLM); // !!! HERE !!! ret = ldap_unbind_s(ldap); On the line marke '!!! HERE !!!' I'd expect 0x31 or any other error returned. Instead I get LDAP_SUCCESS :( Any suggestions? Thx, Milan

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  • Need help in reading callgrind output

    - by n179911
    Hi, I have run callgrind with my application like this "valgrind --tool=callgrind MyApplication" and then call 'callgrind_annotate --auto=yes ./callgrind.out.2489' I see output like 768,097,560 PROGRAM TOTALS -------------------------------------------------------------------------------- Ir file:function -------------------------------------------------------------------------------- 18,624,794 /build/buildd/eglibc-2.11.1/elf/dl-lookup.c:do_lookup_x [/lib/ld-2.11.1.so] 18,149,492 /src/js/src/jsgc.cpp:JS_CallTracer'2 [/src/firefox-debug-objdir/js/src/libmozjs.so] 16,328,897 /src/layout/style/nsCSSDataBlock.cpp:nsCSSExpandedDataBlock::DoAssertInitialState() [/src/firefox-debug-objdir/toolkit/library/libxul.so] 13,376,634 /build/buildd/eglibc-2.11.1/nptl/pthread_getspecific.c:pthread_getspecific [/lib/libpthread-2.11.1.so] 13,005,623 /build/buildd/eglibc-2.11.1/malloc/malloc.c:_int_malloc [/lib/libc-2.11.1.so] 10,404,453 ???:0x0000000000009190 [/usr/lib/libpangocairo-1.0.so.0.2800.0] 10,358,646 /src/xpcom/io/nsFastLoadFile.cpp:NS_AccumulateFastLoadChecksum(unsigned int*, unsigned char const*, unsigned int, int) [/src/firefox-debug-objdir/toolkit/library/libxul.so] 8,543,634 /src/js/src/jsscan.cpp:js_GetToken [/src/firefox-debug-objdir/js/src/libmozjs.so] 7,451,273 /src/xpcom/typelib/xpt/src/xpt_arena.c:XPT_ArenaMalloc [/src/firefox-debug-objdir/toolkit/library/libxul.so] 7,335,131 ???:g_type_check_instance_is_a [/usr/lib/libgobject-2.0.so.0.2400.0] I have a few questions: What does the number on the right mean? Does it mean it spend accumulative that long in calling the function on the right? How can I tell how many times that function has been called and Does that include the time spend in calling the functions called by that function? What does line with ??? mean? e.g. ???:0x0000000000009190 [/usr/lib/libpangocairo-1.0.so.0.2800.0] Thank you.

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  • Rapid calls to fread crashes the application

    - by Slynk
    I'm writing a function to load a wave file and, in the process, split the data into 2 separate buffers if it's stereo. The program gets to i = 18 and crashes during the left channel fread pass. (You can ignore the couts, they are just there for debugging.) Maybe I should load the file in one pass and use memmove to fill the buffers? if(params.channels == 2){ params.leftChannelData = new unsigned char[params.dataSize/2]; params.rightChannelData = new unsigned char[params.dataSize/2]; bool isLeft = true; int offset = 0; const int stride = sizeof(BYTE) * (params.bitsPerSample/8); for(int i = 0; i < params.dataSize; i += stride) { std::cout << "i = " << i << " "; if(isLeft){ std::cout << "Before Left Channel, "; fread(params.leftChannelData+offset, sizeof(BYTE), stride, file + i); std::cout << "After Left Channel, "; } else{ std::cout << "Before Right Channel, "; fread(params.rightChannelData+offset, sizeof(BYTE), stride, file + i); std::cout << "After Right Channel, "; offset += stride; std::cout << "After offset incr.\n"; } isLeft != isLeft; } } else { params.leftChannelData = new unsigned char[params.dataSize]; fread(params.leftChannelData, sizeof(BYTE), params.dataSize, file); }

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  • verifying the signature of x509

    - by sid
    Hi All, While verifying the certificate I am getting EVP_F_EVP_PKEY_GET1_DH My Aim - Verify the certificate signature. I am having 2 certificates : 1. a CA certificate 2. certificate issued by CA. I extracted the 'RSA Public Key (key)' Modulus From CA Certificate using, pPublicKey = X509_get_pubkey(x509); buf_len = (size_t) BN_num_bytes (bn); key = (unsigned char *)malloc (buf_len); n = BN_bn2bin (bn, (unsigned char *) key); if (n != buf_len) LOG(ERROR," : key error\n"); if (key[0] & 0x80) LOG(DEBUG, "00\n"); Now, I have CA public key & CA key length and also having certificate issued by CA in buffer, buffer length & public key. To verify the signature, I have following code int iRet1, iRet2, iRet3, iReason; iRet1 = EVP_VerifyInit(&md_ctx, EVP_sha1()); iRet2 = EVP_VerifyUpdate(&md_ctx, buf, buflen); iRet3 = EVP_VerifyFinal(&md_ctx, (const unsigned char *)CAkey, CAkeyLen, pubkey); iReason = ERR_get_error(); if(ERR_GET_REASON(iReason) == EVP_F_EVP_PKEY_GET1_DH) { LOG(ERROR, "EVP_F_EVP_PKEY_GET1_DH\n"); } LOG(INFO,"EVP_VerifyInit returned %d : EVP_VerifyUpdate returned %d : EVP_VerifyFinal = %d \n", iRet1, iRet2, iRet3); EVP_MD_CTX_cleanup(&md_ctx); EVP_PKEY_free(pubkey); if (iRet3 != 1) { LOG(ERROR,"EVP_VerifyFinal() failed\n"); ret = -1; } LOG(INFO,"signature is valid\n"); I am unable to figure out What might went wrong??? Please if anybody faced same issues? What EVP_F_EVP_PKEY_GET1_DH Error means? Thanks in Advance - opensid

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  • Is it possible to defer member initialization to the constructor body?

    - by Kjir
    I have a class with an object as a member which doesn't have a default constructor. I'd like to initialize this member in the constructor, but it seems that in C++ I can't do that. Here is the class: #include <boost/asio.hpp> #include <boost/array.hpp> using boost::asio::ip::udp; template<class T> class udp_sock { public: udp_sock(std::string host, unsigned short port); private: boost::asio::io_service _io_service; udp::socket _sock; boost::array<T,256> _buf; }; template<class T> udp_sock<T>::udp_sock(std::string host = "localhost", unsigned short port = 50000) { udp::resolver res(_io_service); udp::resolver::query query(udp::v4(), host, "spec"); udp::endpoint ep = *res.resolve(query); ep.port(port); _sock(_io_service, ep); } The compiler tells me basically that it can't find a default constructor for udp::socket and by my research I understood that C++ implicitly initializes every member before calling the constructor. Is there any way to do it the way I wanted to do it, or is it too "Java-oriented" and not feasible in C++? I worked around the problem by defining my constructor like this: template<class T> udp_sock<T>::udp_sock(std::string host = "localhost", unsigned short port = 50000) : _sock(_io_service) { udp::resolver res(_io_service); udp::resolver::query query(udp::v4(), host, "spec"); udp::endpoint ep = *res.resolve(query); ep.port(port); _sock.bind(ep); } So my question is more out of curiosity and to better understand OOP in C++

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  • How to check if two records have a self-referencing relation?

    - by Machine
    Consider the following schema with users and their collegues (friends): Users User: columns: user_id: name: user_id as userId type: integer(8) unsigned: 1 primary: true autoincrement: true first_name: name: first_name as firstName type: string(45) notnull: true last_name: name: last_name as lastName type: string(45) notnull: true email: type: string(45) notnull: true unique: true relations: Collegues: class: User local: invitor foreign: invitee refClass: CollegueStatus equal: true onDelete: CASCADE onUpdate: CASCADE Join table: CollegueStatus: columns: invitor: type: integer(8) unsigned: 1 primary: true invitee: type: integer(8) unsigned: 1 primary: true status: type: enum(8) values: [pending, accepted, denied] default: pending notnull: true Now, let's say I two records, one for the user making a HTTP request (the logged in user), and one record for a user he wants to send a message to. I want to check if these users are collegues. Questions: Does Doctrine have any pre-build functionality to check if two records with with self-relations are related? If not, how would you write a method to check this? Where would you put said method? (In the User-class, UserTable-class etc) I could probably do something like this: public function (User $user1, User $user2) { // Ensure we load collegues if $user1 was fetched with DQL that // doesn't load this relation $collegues = $user1->get('Collegues'); $areCollegues = false; foreach($collegues as $collegue) { if($collegue['userId'] === $user2['userId']) { $areCollegues = true; break; } } return $areCollegues; } But this looks a neither efficient nor pretty. I just feel that it should be solved already for self-referencing relations to be nice to use.

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  • Doctrine2 - relationship

    - by Filip Golonka
    I'm developing an application, which is looking for optimal route and timetable in public transport. I have some experience about Doctrine1, but it's my first time with Doctrine2. There is soem new fields to describe relations (mappedBy and inversedBy) and also some new ways of mapping. I have following code: $query = $this->em->createQuery("SELECT partial cls.{stop}, partial t.{arriveTime, departureTime} FROM \Entities\Timetable t JOIN t.ride r JOIN t.carrierLineStop cls WHERE t.departureTime>=:time AND r.idCarrierLine=:carrierLine AND (cls.idStop=:firstStop OR cls.idStop=:lastStop)"); $query->setParameters(array( 'time' => $time, 'carrierLine' => $path->getLine(), 'firstStop' => $path->getFirstStop(), 'lastStop' => $path->getLastStop() )); When I try to execute that script I've got an error: [Semantical Error] line 0, col 24 near '}, partial t.{arriveTime,': Error: There is no mapped field named 'stop' on class Entities\CarrierLineStop. Mapping files: Entities\CarrierLineStop: type: entity table: carrier_line_stop fields: idCarrierLineStop: id: true type: integer unsigned: false nullable: false column: id_carrier_line_stop generator: strategy: IDENTITY nextStop: type: integer unsigned: false nullable: true column: next_stop manyToOne: idCarrierLine: targetEntity: Entities\CarrierLine cascade: { } mappedBy: null inversedBy: null joinColumns: id_carrier_line: referencedColumnName: id_carrier_line orphanRemoval: false stop: column: id_stop targetEntity: Entities\Stop cascade: { } mappedBy: null inversedBy: carrierLineStop joinColumns: id_stop: referencedColumnName: id_stop orphanRemoval: false lifecycleCallbacks: { } - Entities\Stop: type: entity table: stop fields: idStop: id: true type: integer unsigned: false nullable: false column: id_stop generator: strategy: IDENTITY name: type: string length: 45 fixed: false nullable: true miejscowosc: type: string length: 45 fixed: false nullable: true latitude: type: decimal nullable: true longitude: type: decimal nullable: true oneToMany: carrierLineStop: targetEntity: Entities\CarrierLineStop cascade: { } mappedBy: stop inversedBy: null joinColumns: id_stop: referencedColumnName: id_stop orphanRemoval: false lifecycleCallbacks: { } I have no idea about where the problem is...

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  • C - dns query to structure

    - by Bibo
    I have these structures: typedef struct dnsQuery { char header[12]; struct dnsQuerySection *querySection; } TdnsQuery; typedef struct dnsQuerySection { unsigned char *name; struct dnsQueryQuestion *question; } TdnsQuerySection; typedef struct dnsQueryQuestion { unsigned short qtype; unsigned short qclass; } TdnsQueryQuestion; and I have dns query in byte array from recvfrom. I am trying to get structure from byte array like this: TdnsQuery* dnsQuery = (TdnsQuery*)buf; When I tried to access qtype like this: printf("%u", dnsQuery->querySection->question.qtype); I get seg fault 11. Can someone help me with these structures? What´s wrong with them? I tried to add structure: typedef struct udpPacket { char header[8]; structr dnsQuery query; } and mapped this structure from byte array but it didn´t help. Can someone help me with these structures? How they should look like for dns query with udp protocol?

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  • How to convert Big Endian and how to flip the highest bit?

    - by Robert Frank
    I am using a TStream to read binary data (thanks to this post: http://stackoverflow.com/questions/2878180/how-to-use-a-tfilestream-to-read-2d-matrices-into-dynamic-array). My next problem is that the data is Big Endian. From my reading, the Swap() method is seemingly deprecated. How would I swap the types below? 16-bit two's complement binary integer 32-bit two's complement binary integer 64-bit two's complement binary integer IEEE single precision floating-point - Are IEEE affected by Big Endian? And, finally, since the data is unsigned, the creators of this dataset have stored the unsigned values as signed integers (excluding the IEEE). They instruct that one need only add an offset (2^15, 2^31, and 2^63) to recover the unsigned data. But, they note that flipping the most significant bit is the fastest way to do that. How does one efficiently flip the most significant bit of a 16, 32, or 64-bit integer? So, if the data on disk (16-bit) is "85 FB" - the desired result after reading the data and swapping and bit flipping would be 1531. Is there a way to accomplish the swapping and bit flipping with generics so it fits into the generic answer at the link above? Yes, kids, THIS is how scientific astronomical data is stored by NASA, ESO, and all professional astronomers. This FITS standard is considered by some to be one of the most successful standards ever created in its proliferation and flexibility!

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  • Void* array casting to float, int32, int16, etc.

    - by Griffin
    Hey guys, I've got an array of PCM data, it could be 16 bit, 24 bit packed, 32 bit, etc.. It could be signed, or unsigned, and it could be 32 or 64 bit floating point. It is currently stored as a "void**" matrix, indexed by channel, then by frame. The goal is to allow my library to take in any PCM format and buffer it, without requiring manipulation of the data to fit a designated structure. If the A/D converter spits out 24 bit packed arrays of interleaved PCM, I need to accept it gracefully. I also need to support 16 bit non interleaved, as well as any permutation of the above formats. I know the bit depth and other information at runtime, and I'm trying to code efficiently while not duplicating code. What I need is an effective way to cast the matrix, put PCM data into the matrix, and then pull it out later. I can cast the matrix to int32_t, or int16_t for the 32 and 16 bit signed PCM respectively, I'll probably have to store the 24 bit PCM in an int32_t for 32 bit, 8 bit byte systems as well. Can anyone recommend a good way to put data into this array, and pull it out later? I'd like to avoid large sections of code which look like: switch( mFormat ) { case 1: // unsigned 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (uint8_t*)pcm[i]; break; case 2: // signed 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (int8_t*)pcm[i]; break; case 3: // unsigned 16 bit ... Limitations: I'm working in C/C++, no templates, no RTTI, no STL. Think embedded. Things get trickier when I have to port this to a DSP with 16 bit bytes. Does anybody have any useful macros they might be willing to share? Thanks, -Griff

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  • Unexpected results when looking at ASCII codes in C++.

    - by Columbo
    Hello, The bit of code below is extracting ASCII codes from characters. When I convert characters in the normal ASCII region I get the value I expect. When I convert £ and € from the extened region I get a load of 1's padding the INT that I'm storing the character in. e.g. the output of the below is: 45 (ascii E as expected) FFFFFF80 (extended ascii € as expected but padded with ones) It's not causing me an issue but I'm just wondering why this happens. Here's the code... unsigned int asciichar[3]; string cTextToEncode = "E€"; for (unsigned int i = 0; i < cTextToEncode.length(); i++) { asciichar[i] = (unsigned int)cTextToEncode[i]; cout << hex << asciichar[i] << "\n"; } Can anyone explain why this is? Thanks

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  • C++ 64bit issue

    - by Bobby
    I have the following code: tmp_data = simulated_data[index_data]; unsigned char *dem_content_buff; dem_content_buff = new unsigned char [dem_content_buff_size]; int tmp_data; unsigned long long tmp_64_data; if (!(strcmp(dems[i].GetValType(), "s32"))) { dem_content_buff[BytFldPos] = tmp_data; dem_content_buff[BytFldPos + 1] = tmp_data >> 8; dem_content_buff[BytFldPos + 2] = tmp_data >> 16; dem_content_buff[BytFldPos + 3] = tmp_data >> 24; } if (!(strcmp(dems[i].GetValType(), "f64"))) { dem_content_buff[BytFldPos] = tmp_data; dem_content_buff[BytFldPos + 1] = tmp_data >> 8; dem_content_buff[BytFldPos + 2] = tmp_data >> 16; dem_content_buff[BytFldPos + 3] = tmp_data >> 24; dem_content_buff[BytFldPos + 4] = tmp_data >> 32; dem_content_buff[BytFldPos + 5] = tmp_data >> 40; dem_content_buff[BytFldPos + 6] = tmp_data >> 48; dem_content_buff[BytFldPos + 7] = tmp_data >> 56; } I am getting some weird memory errors in other places of the application when the second if statement is true and executed. When I comment out the 2nd if statement, the problem works fine. So I suspect the way I am performing bitwise operations for 64bit data is incorrect. Can anyone see anything in this code that needs to be corrected?

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  • Access array of c-structs using Python ctypes

    - by sadris
    I have a C-function that allocates memory at the address passed to and is accessed via Python. The pointer contents does contain an array of structs in the C code, but I am unable to get ctypes to access the array properly beyond the 0th element. How can I get the proper memory offset to be able to access the non-zero elements? Python's ctypes.memset is complaining about TypeErrors if I try to use their ctypes.memset function. typedef struct td_Group { unsigned int group_id; char groupname[256]; char date_created[32]; char date_modified[32]; unsigned int user_modified; unsigned int user_created; } Group; int getGroups(LIBmanager * handler, Group ** unallocatedPointer); ############# python code below: class Group(Structure): _fields_ = [("group_id", c_uint), ("groupname", c_char*256), ("date_created", c_char*32), ("date_modified", c_char*32), ("user_modified", c_uint), ("user_created", c_uint)] myGroups = c_void_p() count = libnativetest.getGroups( nativePointer, byref(myGroups) ) casted = cast( myGroups, POINTER(Group*count) ) for x in range(0,count): theGroup = cast( casted[x], POINTER(Group) ) # this only works for the first entry in the array: print "~~~~~~~~~~" + theGroup.contents.groupname Related: Access c_char_p_Array_256 in Python using ctypes

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  • VS2008 Link Error Using SafeInt3.hpp in 64bit mode.

    - by photo_tom
    I have the below code that links and runs fine in 32bit mode - #include "safeint3.hpp" typedef SafeInt<SIZE_T> SAFE_SIZE_T; SAFE_SIZE_T sizeOfCache; SAFE_SIZE_T _allocateAmt; Where safeint3.hpp is current version that can be found on Codeplex SafeInt. For those who are unaware of it, safeint is a template class that makes working with different integer types and sizes "safe". To quote channel 9 video on software - "it writes the code that you should". Which is my case. I have a class that is managing a large in-memory cache of objects (6gb) and I am very concerned about making sure that I don't have overflow/underflow issues on my pointers/sizes/other integer variables. In this use, it solves many problems. My problem is coming when moving from 32bit dev mode to 64bit production mode. When I build the app in this mode, I'm getting the following linker warnings - 1>cachecontrol.obj : warning LNK4006: "bool __cdecl IntrinsicMultiplyUint64(unsigned __int64 const &,unsigned __int64 const &,unsigned __int64 *)" (?IntrinsicMultiplyUint64@@YA_NAEB_K0PEA_K@Z) already defined in ImageInRamCache.obj; second definition ignored 1>cachecontrol.obj : warning LNK4006: "bool __cdecl IntrinsicMultiplyInt64(__int64 const &,__int64 const &,__int64 *)" (?IntrinsicMultiplyInt64@@YA_NAEB_J0PEA_J@Z) already defined in ImageInRamCache.obj; second definition ignored While I understand I can ignore the error, I would like either (a) prevent the warning from occurring or (b) make it disappear so that my QA department doesn't flag it as a problem. And after spending some time researching it, I cannot find a way to do either.

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  • Unicode version of base64 encoding/ decoding

    - by Yan Cheng CHEOK
    I am using base64 encoding/decoding from http://www.adp-gmbh.ch/cpp/common/base64.html It works pretty well with the following code. const std::string s = "I Am A Big Fat Cat" ; std::string encoded = base64_encode(reinterpret_cast<const unsigned char*>(s.c_str()), s.length()); std::string decoded = base64_decode(encoded); std::cout << _T("encoded: ") << encoded << std::endl; std::cout << _T("decoded: ") << decoded << std::endl; However, when comes to unicode namespace std { #ifdef _UNICODE typedef wstring tstring; #else typedef string tstring; #endif } const std::tstring s = _T("I Am A Big Fat Cat"); How can I still make use of the above function? Merely changing std::string base64_encode(unsigned TCHAR const* , unsigned int len); std::tstring base64_decode(std::string const& s); will not work correctly. (I expect base64_encode to return ASCII. Hence, std::string should be used instead of std::tstring)

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  • Store a signed long int (32bit) as 4 octets?

    - by Doori Bar
    I managed to get a unsigned long int octets-representation (BE) by reading IPv4 methods, and I managed to read about how signed integers are using the MSB as the sign indicator, which makes 00 00 00 00 to be 0, while 7F FF FF FF is 2147483647. But I can't manage how to do the same for signed long integers? #include <stdio.h> #include <string.h> int main (void) { unsigned long int intu32; unsigned char octets[4]; intu32 = 255; octets[3] = (intu32) & 255; octets[2] = (intu32 >> 8) & 255; octets[1] = (intu32 >> 16) & 255; octets[0] = (intu32 >> 24) & 255; printf("(%d)(%d)(%d)(%d)\n", octets[0], octets[1], octets[2], octets[3]); intu32 = (octets[0] << 24) | (octets[1] << 16) | (octets[2] << 8) | octets[3]; printf("intu32:%lu\n", intu32); return 0; } Thanks in advance, Doori bar

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  • sql queries slower than expected

    - by neubert
    Before I show the query here are the relevant table definitions: CREATE TABLE phpbb_posts ( topic_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, poster_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, KEY topic_id (topic_id), KEY poster_id (poster_id), ); CREATE TABLE phpbb_topics ( topic_id mediumint(8) UNSIGNED NOT NULL auto_increment ); Here's the query I'm trying to do: SELECT p.topic_id, p.poster_id FROM phpbb_topics AS t LEFT JOIN phpbb_posts AS p ON p.topic_id = t.topic_id AND p.poster_id <> ... WHERE p.poster_id IS NULL; Basically, the query is an attempt to find all topics where the number of times someone other than the target user has posted in is zero. In other words, the topics where the only person who has posted is the target user. Problem is that query is taking a super long time. My general assumption when it comes to SQL is that JOINs of any are super fast and can be done in no time at all assuming all relevant columns are primary or foreign keys (which in this case they are). I tried out a few other queries: SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id; That returns 353340 pretty quickly. I then do these: SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id AND p.poster_id <> 77198; SELECT COUNT(1) FROM phpbb_topics AS t JOIN phpbb_posts AS p ON p.topic_id = t.topic_id WHERE p.poster_id <> 77198; And both of those take quite a while (between 15-30 seconds). If I change the < to a = it takes no time at all. Am I making some incorrect assumptions? Maybe my DB is just foobar'd?

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  • How to easily apply a function to a collection in C++

    - by Jesse Beder
    I'm storing images as arrays, templated based on the type of their elements, like Image<unsigned> or Image<float>, etc. Frequently, I need to perform operations on these images; for example, I might need to add two images, or square an image (elementwise), and so on. All of the operations are elementwise. I'd like get as close as possible to writing things like: float Add(float a, float b) { return a+b; } Image<float> result = Add(img1, img2); and even better, things like complex ComplexCombine(float a, float b) { return complex(a, b); } Image<complex> result = ComplexCombine(img1, img2); or struct FindMax { unsigned currentMax; FindMax(): currentMax(0) {} void operator(unsigned a) { if(a > currentMax) currentMax = a; } }; FindMax findMax; findMax(img); findMax.currentMax; // now contains the maximum value of 'img' Now, I obviously can't exactly do that; I've written something so that I can call: Image<float> result = Apply(img1, img2, Add); but I can't seem to figure out a generic way for it to detect the return type of the function/function object passed, so my ComplexCombine example above is out; also, I have to write a new one for each number of arguments I'd like to pass (which seems inevitable). Any thoughts on how to achieve this (with as little boilerplate code as possible)?

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  • MySQL query problem

    - by Luke
    Ok, I have the following problem. I have two InnoDB tables: 'places' and 'events'. One place can have many events, but event can be created without entering place. In this case event's foreign key is NULL. Simplified structure of the tables looks as follows: CREATE TABLE IF NOT EXISTS `events` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, `places_id` int(9) unsigned DEFAULT NULL, PRIMARY KEY (`id`), KEY `fk_events_places` (`places_id`), ) ENGINE=InnoDB; ALTER TABLE `events` ADD CONSTRAINT `events_ibfk_1` FOREIGN KEY (`places_id`) REFERENCES `places` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION; CREATE TABLE IF NOT EXISTS `places` ( `id` int(9) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, PRIMARY KEY (`id`), ) ENGINE=InnoDB; Question is, how to construct query which contains name of the event and name of the corresponding place (or no value, in case there is no place assigned?). I am able to do it with two queries, but then I am visibly separating events which have place assigned from the ones that are without place. Help really appreciated.

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  • Error in value of default parameter [Bug in Visual C++ 2008?]

    - by HellBoy
    I am facing following issue while trying to use template in my code I have some C++ code which i call from C functions. Problem is I am getting different values in the following code for statement 1 and 2. Type id : unsigned int statement 1 : 4 statement 2 : 1 C++ Code : template <typename T> void func(T* value, unsigned int len = sizeof(T)) { cout << "Type id : " << typeid(T).name() << endl; cout << "statement 1 " << sizeof(T) << endl; cout << "statement 2 " << len << endl; } template <typename T> void func1(T data) { T val = data; func(&val); } C Code : void test(void *ptr, unsigned int len) { switch(len) { case 1: func1(*(static_cast<uint32_t *>(ptr)) break; } } This happens only on windows. On Linux it works fine.

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  • Misaligned Pointer Performance

    - by Elite Mx
    Aren't misaligned pointers (in the BEST possible case) supposed to slow down performance and in the worst case crash your program (assuming the compiler was nice enough to compile your invalid c program). Well, the following code doesn't seem to have any performance differences between the aligned and misaligned versions. Why is that? /* brutality.c */ #ifdef BRUTALITY xs = (unsigned long *) ((unsigned char *) xs + 1); #endif ... /* main.c */ #include <stdio.h> #include <stdlib.h> #define size_t_max ((size_t)-1) #define max_count(var) (size_t_max / (sizeof var)) int main(int argc, char *argv[]) { unsigned long sum, *xs, *itr, *xs_end; size_t element_count = max_count(*xs) >> 4; xs = malloc(element_count * (sizeof *xs)); if(!xs) exit(1); xs_end = xs + element_count - 1; sum = 0; for(itr = xs; itr < xs_end; itr++) *itr = 0; #include "brutality.c" itr = xs; while(itr < xs_end) sum += *itr++; printf("%lu\n", sum); /* we could free the malloc-ed memory here */ /* but we are almost done */ exit(0); } Compiled and tested on two separate machines using gcc -pedantic -Wall -O0 -std=c99 main.c for i in {0..9}; do time ./a.out; done

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