c

Is there a practical benefit to casting a NULL pointer to an object and calling one of its member functions?

Ok, so I know that technically this is undefined behavior, but nonetheless, I've seen this more than once in production code. And please correct me if I'm wrong, but I've also heard that some people use this "feature" as a somewhat legitimate substitute for a lacking aspect of the current C++ standard, namely, the inability to obtain the...

String search algorithm used by string::find() c++

how its faster than cstring functions? is the similar source available for C? ...

Learning from Java to C... ...What is the biggest challenge?

I had experience on Java, because of some results, I need to code in C, is it difficult to switch from Java to C? And what is the biggest different between these two languages? ...

fputs crashing in C on Mac with Xcode

Hi, I have a command line app and have the code chdir("/var"); FILE *scriptFile = fopen("wiki.txt", "w"); fputs("tell application \"Firefox\"\n activate\n",scriptFile); fclose(scriptFile); and when I run it in Xcode I get an EXC_BAD_ACCESS when it gets to the first fputs(); call ...

PIC C - Sending 200 values over USB, but it only sends 25 or so of them...

I have a PIC18F4455 microcontroller which I am trying to use to send 200 values over USB. Basically I am using a for loop and a printf statement to print the values to the usb output stream. However, when the code executes I see in my serial port monitor that it is only sending the first 25 or so values, then stopping. My PIC C code i...

malloc and delete in C++, opinions

In C++ using delete to free memory obtained with malloc() doesn't necessarily cause a program to blow up. Do you guys think a warning or perhaps even an assertion failure should be produced if delete is used to free memory obtained using malloc()?? Why do you think that Stroustrup did not had this feature on C++? ...

How does compiler use lib file ?

I am curious about how c/c++ compiler analyse lib files ? I mean say I create a library containing some classes, I am using that library in my main program. How does compiler know what class names are there in that library. Of course that information is present in binary format, I want to use that functionality in my program, to be speci...

specified path to enter into c

may i know how to get into c programming.that is may i know a specified path ...

Why is this not a bug in qmail?

I was reading DJB's "Some thoughts on security after ten years of Qmail 1.0" and he listed this function for moving a file descriptor: int fd_move(to,from) int to; int from; { if (to == from) return 0; if (fd_copy(to,from) == -1) return -1; close(from); return 0; } It occurred to me that this code does not check the return va...

Why we used double and triple pointer in objective-C or C language?

Hi, I confused when i want to take single pointer and when should i take double pointer? In following structure what exactly did? struct objc_class { Class isa; Class super_class; const char *name; long version; long info; long instance_size; struct objc_ivar_list *ivars; struct objc_method_list **method...

GDB Not Skipping Functions without Debug Info

I compiled GDB 7 on a Mac OS X Leopard system. When stepping through a C program, GDB fails to step through 'printf()' statements, which probably don't have associated debug information, and starts printing "Cannot find bounds of current function." Here's some output: $ /usr/local/bin/gdb try1 GNU gdb (GDB) 7.1 Copyright (C) 2010 Free...

How to write a "thread safe" function in C ?

Hello I am writing some data structures in C, and I've realized that their associated functions aren't thread safe. The i am writing code uses only standard C, and I want to achieve some sort of 'synchronization'. I was thinking to do something like this: enum sync_e { TRUE, FALSE }; typedef enum sync_e sync; struct list_s { //Other ...

Need to format character precedence in Strings.

I'm currently writing a Roman Numeral Converter for the fun of it. The problem works up to the aforementioned character precedence. Since Roman Numerals are not positional, i.e. III does not symbolize 1*whatever base^2 + 1*whatever base^1 + 1*whatever base^0. That of course makes it hard when somebody types in XIV and I need to make su...

Conditional operator in C

can every if...then...else statement be converted into an equivalent statement using only ?: ...

pthread and child process data sharing in C

hi everyone, my question is somewhat conceptual, how is parent process' data shared with child process created by a fork() call or with a thread created by pthread_create() for example, are global variables directly passed into child process and if so, does modification on that variable made by child process effect value of it in pare...

Endianness manipulation - is there a C library for this?

Hi all, With the sort of programs I write (working with raw file data) I often need functions to convert between big and little endian. Usually I write these myself (which is covered by many other posts here) but I'm not that keen on doing this for a number of reasons - the main one being lack of testing. I don't really want to spend ...

C code to round numbers

Is there any way to round numbers in C? I do not want to use ceil and floor. Is there any other alternative? I came across this code snippet when I Googled for the answer: (int)(num < 0 ? (num - 0.5) : (num + 0.5)) The above line always prints the value as 4 even when float num =4.9. Please suggest a solution. ...

C Nested Structure Pointer Problem

I have a shared structure, and inside it a request structure: struct shared_data { pthread_mutex_t th_mutex_queue; struct request_queue { int min; int max; char d_name[DIR_SIZE]; pid_t pid; int t_index; } request_queue[BUFSIZE]; int count; int data_buffer_allocation[BUFSIZE]...

Transform OpenCV image data type to Devil image format and vice-verca

I want to use a CUDA-enabled SIFT library but I am using the OpenCV driver to get images from the webcam? The Cuda library is using the Devil Library for image data types. Should I transofrm the images from OpenCV data types to Devil? Or Should I use another method for getting images from the webcam[devil compatible data types]? Thanks f...

C Structure Pointer Problem

I have this struct; #define BUFSIZE 10 struct shared_data { pthread_mutex_t th_mutex_queue; int count; int data_buffer_allocation[BUFSIZE]; int data_buffers[BUFSIZE][100]; }; and I want to allocate one of the data_buffers for a process, for that purpose I execute the following function; int allocate_data_buffer(int p...