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  • C : Memory layout of C program execution

    - by pavun_cool
    Hi All , I wanted know how the kernel is providing memory for simple C program . For example : #include<stdio.h> #include<malloc.h> int my_global = 10 ; main() { char *str ; static int val ; str = ( char *) malloc ( 100 ) ; scanf ( "%s" , str ) ; printf( " val:%s\n",str ) ; } See, In this program I have used static , global and malloc for allocating dynamic memory So , how the memory lay out will be ... ? Any one give me url , which will have have details information about this process..

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  • Using pipes inside a class in C++

    - by Paul
    I'm trying to use this tutorial to make plots with Gnuplot in C++. However I will be using the pipe to Gnuplot from within a class, but then I run into some problems: I've got a header file where I declare all variables etc. I need to declare the pipe-variable here too, but how do I do that? I've tried doing it straight away, but it doesn't work: Logger.h: class Logger { FILE pipe; } Logger.cpp: Logger::Logger() { //Constructor *pipe = popen("gnuplot -persist","w"); } Gives the error Logger.cpp:28: error: no match for ‘operator=’ in ‘*((Logger*)this)->Logger::pipe = popen(((const char*)"gnuplot -persist"), ((const char*)"w"))’ Suggestions?

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  • How can I tell if an ADODB::_RecordsetPtr has already been created?

    - by scottm
    I am trying to write a class that uses ADO to retrieve SQL records. The intent is for the class to maintain one private recordset an other methods move forward, retrieve fields, etc. This is a basic example of my class: class SqlADO { private: ADODB::_RecordsetPtr m_recordset; public: void Open(); //open the connection void Execute(const char* sql); // creates or replaces current recordset void Next(); //moves recordset cursor forward void Field(const char* fieldName); //retrieves field name from current record of the recordset }; My Questions: In the Execute method, how can I check to see that the recordset instance has been created (or do I need to) so that I can close it first? Do you know of any good ADO COM Interop references?

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  • How do I get characters common to two vectors in C++?

    - by Sam Phelps
    I am trying to compare two vector objects, and return a single vector containing all the chars which appear in both vectors. How would I go about this without writing some horribly complex manual method which compares every char in the first vector to every char in the second vector and using an if to add it to a third vector (which would be returned) if they match. Maybe my lack of real experience with vectors is making me imagine this will be harder than it really is, but I suspect there is some simplier way which I have been unable to find through searching.

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  • Need help with displaying the message correctly in the pole display always starting at the beginning

    - by SA
    Hi, I am using an HP RS232 pole display with the following setting: Char type: USA/Europe (default) Command mode: EPSON (default) Baud rate: 9600, n , 8, 1 (default?) Passthru None (Default) Here's the code using System.IO.Ports; private SerialPort port; port = new SerialPort("COM2", 9600, Parity.None, 8, StopBits.One); port.Handshake = Handshake.None; Port.WriteLine("Welocome to something something"); It has 2 lines consisting of 20 characters each with a total of 40 characters. I have no control how and where the characters get displayed. I would like it to always begin on line 1 position 1 but as I said earlier how would I be able to do that. The same program if I run again and again it moves a character to the left. I have set it to accept ASCII char set and so I am able to type as is visble in the Writeline message

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  • Why isn't my IO executed in order?

    - by HaskellElephant
    Hi, I'm having some fun learning about the haskell IO. However in my recent exploration of it I have encountered some problems with IO not executing in order, even inside a do construct. In the following code I am just keeping track of what cards are left, where the card is a tuple of chars (one for suit and one for value) then the user is continously asked for wich cards have been played. I want the putStr to be executed between each input, and not at the very end like it is now. module Main where main = doLoop cards doLoop xs = do putStr $ show xs s <- getChar n <- getChar doLoop $ remove (s,n) xs suits = "SCDH" vals = "A23456789JQK" cards = [(s,n) | s <- suits, n <- vals] type Card = (Char,Char) remove :: Card -> [Card] -> [Card] remove card xs = filter (/= card) xs

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  • Simple doubt related to strings in C (question in an interview)

    - by piemesons
    // The first example: char text[] = "henri"; char *p; p = text; *(p + 1) = 'E'; // Output = hEnri // Now If we want to remove the "e" ie hnri, we would go for????? *(p + 1)=????? Please dont say start copying the array. I am looking for the best solution. Its an interview question... EDIT I specially mentioned the question that i am not asking for the solution like start moving the element. I thought there must be some other good solution..

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  • Cocoa multhithreads, locks don't work

    - by Igor
    I have a threadMethod which shows in console robotMotorsStatus every 0.5 sec. But when I try to change robotMotorsStatus in changeRobotStatus method I receive an exception. Where I need to put locks in that program. #import "AppController.h" @implementation AppController extern char *robotMotorsStatus; - (IBAction)runThread:(id)sender { [self performSelectorInBackground:@selector(threadMethod) withObject:nil]; } - (void)threadMethod { char string_to_send[]="QFF001100\r"; //String prepared to the port sending (first inintialization) string_to_send[7] = robotMotorsStatus[0]; string_to_send[8] = robotMotorsStatus[1]; while(1){ [theLock lock]; usleep(500000); NSLog (@"Robot status %s", robotMotorsStatus); [theLock unlock]; } } - (IBAction)changeRobotStatus:(id)sender { robotMotorsStatus[0]='1'; }

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  • [c]how to take input for a character pionter without using fget?

    - by ashish yadav
    consider the code include int main() {char* a; scanf("%s",a);//&a and &a[0] give same results-crashes printf("%s",); return 0; } why does this code results in crashing?whereas this code using character array works fine? include int main() {char a[100]; scanf("%s",&a[0]);//works fine printf("%s",a); return 0; } the difference being character array and pointer?but i knew that pointer just points to the first element that is &a[0] should work fine but upper code crashes for all three that is a,&a and &a[0]? the main thing i would to gather is how can i take input of a character pointer if i insist on using scanf only? i apologize if i am not clear. thanks in advance:)

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  • [c++] upload image to imageshack

    - by cinek1lol
    Hi. I would like to send pictures via a program written in C + + I wrote such a thing using curl.exe WinExec("C:\\curl\\curl.exe -H Expect: -F \"fileupload=@C:\\curl\\ok.jpg\" -F \"xml=yes\" -# \"http://www.imageshack.us/index.php\" -o data.txt -A \"Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1\" -e \"http://www.imageshack.us\"", NULL); This only works that I would like to send pictures to a variable pre-loaded char (you know what I mean? first reads the pictures into a variable and then send that variable), because now I have to specify the path to the images on disk I wanted to make this program was written in C + + using the curl library, and not the exe. I found it such a program (which some have modified) #include <stdio.h> #include <string.h> #include <iostream> #include <curl/curl.h> #include <curl/types.h> #include <curl/easy.h> int main(int argc, char *argv[]) { CURL *curl; CURLcode res; struct curl_httppost *formpost=NULL; struct curl_httppost *lastptr=NULL; struct curl_slist *headerlist=NULL; static const char buf[] = "Expect:"; curl_global_init(CURL_GLOBAL_ALL); /* Fill in the file upload field */ curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "send", CURLFORM_FILE, "nowy.jpg", CURLFORM_END); curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "nowy.jpg", CURLFORM_COPYCONTENTS, "nowy.jpg", CURLFORM_END); curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "submit", CURLFORM_COPYCONTENTS, "send", CURLFORM_END); curl = curl_easy_init(); headerlist = curl_slist_append(headerlist, buf); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "http://www.imageshack.us/index.php"); if ( (argc == 2) && (!strcmp(argv[1], "xml=yes")) ) curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist); curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost); res = curl_easy_perform(curl); curl_easy_cleanup(curl); curl_formfree(formpost); curl_slist_free_all (headerlist); } system("pause"); return 0; } I will be grateful for any help

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  • Create a modifiable string literal in C++

    - by Anne
    Is it possible to create a modifiable string literal in C++? For example: char* foo[] = { "foo", "foo" }; char* afoo = foo[0]; afoo[2] = 'g'; // access violation This produces an access violation because the "foo"s are allocated in read only memory (.rdata section I believe). Is there any way to force the "foo"s into writable memory (.data section)? Even via a pragma would be acceptable! (Visual Studio compiler) I know I can do strdup and a number of other things to get around the problem, but I want to know specifically if I can do as I have asked. :)

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  • how to send Zip(binary) file Through HTTP post method in mFC/C++?

    - by Mahantesh
    I am posting the file to server and its working fine, But the my code fails when i try to post the .zip file. May be my code is wrong in the reading the zip file contents data. ifstream::pos_type size; char * memblock; ifstream file ("example.zip", ios::in|ios::binary|ios::ate); if (file.is_open()) { size = file.tellg(); memblock = new char [size]; file.seekg (0, ios::beg); file.read (memblock, size); file.close(); postBody.AppendFormat("Content-Disposition: form-data; name=\"datafile\"; filename=\"%s\"; \r\n\n%s", zipFilePath, memblock); postBody.AppendFormat("\r\n--%s--\r\n", boundary); }

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  • Preprocessor directive to test if this is C or C++

    - by Collin
    I'm trying to find a standard macro which will test whether a header file is being compiled as C or as C++. The purpose of this is that the header may be included by either C or C++ code, and must behave slightly differently depending on which. Specifically: In C, I need this to be the code: extern size_t insert (const char*); In C++, I need this to be the code: extern "C" size_t insert (const char*); Additionally, is there a way to avoid putting #ifdef's around every declaration in the header?

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  • Perfect Forwarding to async lambda

    - by Alexander Kondratskiy
    I have a function template, where I want to do perfect forwarding into a lambda that I run on another thread. Here is a minimal test case which you can directly compile: #include <thread> #include <future> #include <utility> #include <iostream> #include <vector> /** * Function template that does perfect forwarding to a lambda inside an * async call (or at least tries to). I want both instantiations of the * function to work (one for lvalue references T&, and rvalue reference T&&). * However, I cannot get the code to compile when calling it with an lvalue. * See main() below. */ template <typename T> std::string accessValueAsync(T&& obj) { std::future<std::string> fut = std::async(std::launch::async, [](T&& vec) mutable { return vec[0]; }, std::forward<T>(obj)); return fut.get(); } int main(int argc, char const *argv[]) { std::vector<std::string> lvalue{"Testing"}; // calling with what I assume is an lvalue reference does NOT compile std::cout << accessValueAsync(lvalue) << std::endl; // calling with rvalue reference compiles std::cout << accessValueAsync(std::move(lvalue)) << std::endl; // I want both to compile. return 0; } For the non-compiling case, here is the last line of the error message which is intelligible: main.cpp|13 col 29| note: no known conversion for argument 1 from ‘std::vector<std::basic_string<char> >’ to ‘std::vector<std::basic_string<char> >&’ I have a feeling it may have something to do with how T&& is deduced, but I can't pinpoint the exact point of failure and fix it. Any suggestions? Thank you! EDIT: I am using gcc 4.7.0 just in case this could be a compiler issue (probably not)

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  • What are the implications of using static const instead of #define?

    - by Simon Elliott
    gcc complains about this: #include <stdio.h> static const int YY = 1024; extern int main(int argc, char*argv[]) { static char x[YY]; } $ gcc -c test1.c test1.c: In function main': test1.c:5: error: storage size of x' isn't constant test1.c:5: error: size of variable `x' is too large Remove the “static” from the definition of x and all is well. I'm not exactly clear what's going on here: surely YY is constant? I had always assumed that the "static const" approach was preferable to "#define". Is there any way of using "static const" in this situation?

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  • java decmail string to AS 3.0 conversion procedure

    - by Jack Smith
    Hello, I have a problem with conversion java code to action script 3. Anyone can help with code translation? Thanks. public static short[] decmail_str_to_binary_data(String s) { short[] data = new short[s.length()/2]; for (int i = 0; i < s.length(); i += 2) { char c1 = s.charAt(i); char c2 = s.charAt(i + 1); int comb = Character.digit(c1, 16) & 0xff; comb <<= 4; comb += Character.digit(c2, 16) & 0xff; data[i/2] = (short)comb; } return data; }

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  • Use C function in C++ program; "multiply-defined" error

    - by eom
    I am trying to use this code for the Porter stemming algorithm in a C++ program I've already written. I followed the instructions near the end of the file for using the code as a separate module. I created a file, stem.c, that ends after the definition and has extern int stem(char * p, int i, int j) ... It worked fine in Xcode but it does not work for me on Unix with gcc 4.1.1--strange because usually I have no problem moving between the two. I get the error ld: fatal: symbol `stem(char*, int, int)' is multiply-defined: (file /var/tmp//ccrWWlnb.o type=FUNC; file /var/tmp//cc6rUXka.o type=FUNC); ld: fatal: File processing errors. No output written to cluster I've looked online and it seems like there are many things I could have wrong, but I'm not sure what combination of a header file, extern "C", etc. would work.

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  • How to get size of file in visual c++?

    - by karikari
    Below is my code. My problem is, my destination file always has a lot more strings than the originating file. Then, inside the for loop, instead of using i < sizeof more, I realized that I should use i < sizeof file2 . Now my problem is, how to get the size of file2? int i = 0; FILE *file2 = fopen(LOG_FILE_NAME,"r"); wfstream file3 (myfile, ios_base::out); // char more[1024]; char more[SIZE-OF-file2]; for(i = 0; i < SIZE-OF-file2 ; i++) { fgets(more, SIZE-OF-file2, file2); file3 << more; } fclose(file2); file3.close();

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  • jquery ui autcomplete does not disapper with no result

    - by mike
    Hi, I'm using jquery ui autocomplete with the following code: $('#company').autocomplete({ source: function(request, response) { var company_name = $('#company').val(); $.ajax({ type: 'post', url: 'http://new.admin.localhost/client/helper/lookup_company_name', cache: false, data: { company : company_name }, dataType: 'json', success: function(data) { //alert(data); response($.map(data.companies, function(item) { return { label: item.company, value: item.company } })) } }) }, minLength: 2, }); This works as expected... The problem is, if the first few chars match something and then you enter a char that should "break" any match, it just keeps the drop down in place with the results for the last matched char... make sense? Would this be something I needed to change in the script that returns the data or something in the jquery? thanks!

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  • Is there any memory leak in the normal routine of sqlite3_*()?

    - by reer
    A normal routine of sqlite3_prepare_v2() + sqlite3_step() + sqlite3_finalize() could contain leak. It sound ridiculous. But the test code seems to say it. Or I used the sqlite3_*() wrongly. Appreciate for any reply. __code________________________ include include // for usleep() include int multi_write (int j); sqlite3 *db = NULL; int main (void) { int ret = -1; ret = sqlite3_open("test.db", &db); ret = sqlite3_exec(db,"CREATE TABLE data_his (id INTEGER PRIMARY KEY, d1 CHAR(16))", NULL,NULL,NULL); usleep (100000); int j=0; while (1) { multi_write (j++); usleep (2000000); printf (" ----------- %d\n", j); } ret = sqlite3_close (db); return 0; } int multi_write (int j) { int ret = -1; char *sql_f = "INSERT OR REPLACE INTO data_his VALUES (%d, %Q)"; char *sql = NULL; sqlite3_stmt *p_stmt = NULL; ret = sqlite3_prepare_v2 (db, "BEGIN TRANSACTION", -1, &p_stmt, NULL); ret = sqlite3_step ( p_stmt ); ret = sqlite3_finalize ( p_stmt ); int i=0; for (i=0; i<100; i++) { sql = sqlite3_mprintf ( sql_f, j*100000 + i, "00000000000068FD"); ret = sqlite3_prepare_v2 (db, sql, -1, &p_stmt, NULL ); sqlite3_free ( sql ); //printf ("sqlite3_prepare_v2(): %d, %s\n", ret, sqlite3_errmsg (db)); ret = sqlite3_step ( p_stmt ); //printf ("sqlite3_step(): %d, %s\n", ret, sqlite3_errmsg (db)); ret = sqlite3_finalize ( p_stmt ); //printf ("sqlite3_finalize(): %d, %s\n\n", ret, sqlite3_errmsg (db)); } ret = sqlite3_prepare_v2 (db, "COMMIT TRANSACTION", -1, &p_stmt, NULL ); ret = sqlite3_step ( p_stmt ); ret = sqlite3_finalize ( p_stmt ); return 0; } __result________________________ And I watch the the process's run by top. At first, the memory statistics is: PID PPID USER STAT VSZ %MEM %CPU COMMAND 17731 15488 root S 1104 5% 7% ./sqlite3multiwrite When the printf() in while(1){} of main() prints the 150, the memory statistics is: PID PPID USER STAT VSZ %MEM %CPU COMMAND 17731 15488 root S 1552 5% 7% ./sqlite3multiwrite It sounds that after 150 for-cycles, the memory used by sqlite3multiwrite increase from 1104KB to 1552KB. What does it mean? memory leak or other thing?

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  • Declaring a data type dynamically in C++

    - by Bobby
    I want to be able to do the following: I have an array of strings that contain data types: string DataTypeValues[20] = {"char", "unsigned char", "short", "int"}; Then later, I would like to create a variable of one of the data types at runtime. I won't know at compile time what the correct data type should be. So for example, if at runtime I determined a variable x needed to be of type int: DataTypeValues[3] x = 100; Obviously this won't work, so how could I do something like this?

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  • How can I obtain the IPv4 address of the client?

    - by Dr Dork
    Hello! I'm prepping for a simple work project and am trying to familiarize myself with the basics of socket programming in a Unix dev environment. At this point, I have some basic server side code setup to listen for incoming TCP connection requests from clients after the parent socket has been created and is set to listen... int sockfd, newfd; unsigned int len; socklen_t sin_size; char msg[]="Test message sent"; char buf[MAXLEN]; int st, rv; struct addrinfo hints, *serverinfo, *p; struct sockaddr_storage client; char ip[INET6_ADDRSTRLEN]; . . //parent socket creation and listen code omitted for simplicity . //wait for connection requests from clients while(1) { //Returns the socketID and address of client connecting to socket if( ( newfd = accept(sockfd, (struct sockaddr *)&client, &len) ) == -1 ){ perror("Accept"); exit(-1); } if( (rv = recv(newfd, buf, MAXLEN-1, 0 )) == -1) { perror("Recv"); exit(-1); } struct sockaddr_in *clientAddr = ( struct sockaddr_in *) get_in_addr((struct sockaddr *)&client); inet_ntop(client.ss_family, clientAddr, ip, sizeof ip); printf("Receive from %s: query type is %s\n", ip, buf); if( ( st = send(newfd, msg, strlen(msg), 0)) == -1 ) { perror("Send"); exit(-1); } //ntohs is used to avoid big-endian and little endian compatibility issues printf("Send %d byte to port %d\n", ntohs(clientAddr->sin_port) ); close(newfd); } } I found the get_in_addr function online and placed it at the top of my code and use it to obtain the IP address of the client connecting... // get sockaddr, IPv4 or IPv6: void *get_in_addr(struct sockaddr *sa) { if (sa->sa_family == AF_INET) { return &(((struct sockaddr_in*)sa)->sin_addr); } return &(((struct sockaddr_in6*)sa)->sin6_addr); } but the function always returns the IPv6 IP address since thats what the sa_family property is set as. My question is, is the IPv4 IP address stored anywhere in the data I'm using and, if so, how can I access it? Thanks so much in advance for all your help!

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  • Please see following code and answer

    - by user323422
    template <class T> class _cExplicitInstation { public: void show1(T c) { double d =10.02 ; std::cout<<c; } void show2(T d) { std::cout<<d; } }; template _cExplicitInstation<char>; template void _cExplicitInstation<int>::show1(int c); int main() { _cExplicitInstation<char> abc; _cExplicitInstation<int>().show2(10);// it should show error as i have // explicitly declare for show1() function but its working // can u tell why? }

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  • c: memory allocation (what's going on)

    - by facha
    Hi, everyone Please take a look at this piece of code. I'm allocating one byte for the first variable and another byte for the second one. However, it seems like the compiler allocates more (or I'm missing something). The program outputs both strings, even though their length is more the one byte. void main() { char* some1 = malloc(1); sprintf(some1,"cool"); char* some2 = malloc(1); sprintf(some2,"face"); printf("%s ",some1); printf("%s\n",some2); } Please, could anyone spot some light on what's going on when memory is being allocated.

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  • Storing objects in STL vector - minimal set of methods

    - by osgx
    Hello What is "minimal framework" (necessary methods) of object, which I will store in STL <vector>? For my assumptions: #include <vector> #include <cstring> using namespace std; class Doit { private: char *a; public: Doit(){a=(char*)malloc(10);} ~Doit(){free(a);} }; int main(){ vector<Doit> v(10); } gives *** glibc detected *** ./a.out: double free or corruption (fasttop): 0x0804b008 *** Aborted and in valgrind: malloc/free: 2 allocs, 12 frees, 50 bytes allocated.

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