Recent questions tagged C

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c - Valgrind reports memory 'possibly lost' when using glib data types

I'm developing a library using a number of glib datastructures (GHashTable, GSList etc.). I've been checking my ... CentOS release 5.5 (Final) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Is #if defined MACRO equivalent to #ifdef MACRO?

I have code that I want to have two modes, debug and verbose. I define them in my header file as, ... /disabling a particular section of code? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - SQLite3 and multiple processes

How should one ensure correctness when multiple processes access one single SQLite database file? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Converting color value from float 0..1 to byte 0..255

What would be the correct way of converting color value from float to byte? At first I thought b=f*255.0 should do it, ... : (int)((f)*256.0)) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How to use pkg-config in Make

I want to compile the simplest GTK program. I can compile it using the command line: gcc $(pkg-config -- ... in advance for your kind help. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What is the cause of flexible array member not at end of struct error?

I am wondering why I keep getting error: flexible array member not at end of struct error when I call malloc. ... the correct call to malloc? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - warning: assignment makes integer from pointer without a cast

When I declare a char * to a fixed string and reuse the pointer to point to another string /* initial ... recast the pointer but no success. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c preprocessor - What is the use of the #error directive in C?

What is the #error directive in C? What is the use of it? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What's meaning of "EXPORT_SYMBOL" in Linux kernel code?

from here 48 struct snd_card *snd_cards[SNDRV_CARDS]; 49 EXPORT_SYMBOL(snd_cards); I am not getting whats the meaning ... the meaning of that. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - "fatal error: bits/libc-header-start.h: No such file or directory" while compiling HTK

I'm getting the following issue when trying to run make on the HTK library: (cd HTKLib && make HTKLib.a ... retrieve the missing 32 bit library. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Pointers with two dimensional array

Please consider the following piece of code #include <stdio.h> #define ROW_SIZE 2 #define COL_SIZE 2 int main() ... being same. Please explain. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - SDL2.0 Alternative for SDL_Overlay

So I've been trying to go through the following tutorial on ffmpeg: http://dranger.com/ffmpeg/tutorial02. ... height, SDL_YV12_OVERLAY, screen); See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Why is my pointer not null after free?

void getFree(void *ptr) { if(ptr != NULL) { free(ptr); ptr = NULL; } return; } int main() { char * ... is the output of this program not NULL? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - x86 Assembly: INC and DEC instruction and overflow flag

In x86 assembly, the overflow flag is set when an add or sub operation on a signed integer overflows, and the ... overflow flag in this case? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - So what does "return 0" actually mean?

I'm pretty proficient in PHP, but I've started dabbling with C. I've seen the code return 0; at the end ... throws up haven't been that concise. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - malloc - invalid conversion from void* to double*

I want to write a function that creates a copy of a double array using pointers. This is my code so far: ... understand what I'm doing wrong. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - When do we need to use posix_memalign instead of malloc?

Seems posix_memalign let you choose a customized alignment,but when is that necessary? malloc has already done the ... /src/core/ngx_palloc.c See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Find the size of a string pointed by a pointer

#include <stdio.h> int main () { char *ptr = "stackoverflow" } Is there any way to find the length of ... ptr, as sizeof ptr always gives 4 See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Process name from its pid in linux

How to get a process name from his pid ? For example I execute cat file1.txt, but I want to figure out ... it or something similar? Any idea? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How to sum large numbers?

I am trying to calculate 1 + 1 * 2 + 1 * 2 * 3 + 1 * 2 * 3 * 4 + ... + 1 * 2 * ... * n where n ... sum += P; } printf("%lu", sum); return 0; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What's the reason for letting the semantics of a=a++ be undefined?

a = a++; is undefined behaviour in C. The question I am asking is : why? I mean, I get that it ... then feedback and/or changes are welcome) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How can I wait for any/all pthreads to complete?

I just want my main thread to wait for any and all my (p)threads to complete before exiting. The threads come and ... -and-dirty way to do this? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Why is select used in Linux

I was going through a serial program and I observed that they use select() before using read(). Why exactly is ... already has the value of fd See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Define functions in structs

Can we define functions in structs in C programming language? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Getting the saved instruction pointer address from a signal handler

My question is somewhat different from others that have asked about fault addresses. I'm trying to implement a ... also like to hear reasons. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - dereferencing pointer to integer array

I have a pointer to integer array of 10. What should dereferencing this pointer give me? Eg: #include<stdio.h> main ... 't *ptr print 1? } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - GCC SSE code optimization

This post is closely related to another one I posted some days ago. This time, I wrote a simple code that just ... What's the reason for that? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - CUDA: Tiled matrix-matrix multiplication with shared memory and matrix size which is non-multiple of the block size

I'm trying to familiarize myself with CUDA programming, and having a pretty fun time of it. I'm ... m missing something really fundamental. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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