Recent questions tagged C

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c - Why does gcc allow arguments to be passed to a function defined to be with no arguments?

I don't get why does this code compile? #include <stdio.h> void foo() { printf("Hello "); } int main() ... to foo(). Is this expected behavior? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How to buffer stdout in memory and write it from a dedicated thread

I have a C application with many worker threads. It is essential that these do not block so where the ... -party libraries). Thoughts? NickB See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Sizeof vs Strlen

#include <stdio.h> #include <string.h> int main(int argc, char *argv[]) { char string[] = "october"; ... something wrong with my syntax or what? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How to implement Bitcount using only Bitwise operators?

The task is to implement a bit count logic using only bitwise operators. I got it working fine, but am wondering if ... 3) & 0x1); Thank you. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Is there a macro definition to check the Linux kernel version?

I'm wondering if there is a gcc macro that will tell me the Linux kernel version so I can set variable types ... my own macro that does this? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How does sig_atomic_t actually work?

How does the compiler or OS distinguish between sig_atomic_t type and a normal int type variable, and ensures ... make the operation atomic? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Using pipe to pass integer values between parent and child

I'm a little confused on how to properly use pipe() to pass integer values between two processes. In my ... fivecount,threecount); return 0; } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - how to correctly use fork, exec, wait

The shell i'm writing needs to execute a program given to it by the user. Here's the very shortened simplified ... ; execve(hold, argv, envp); See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How can I find the number of elements in an array?

I have an int array and I need to find the number of elements in it. I know it has something to do with ... not sure how to use it exactly. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Embedding HWND into external process using SetParent

I'm trying to embed a window from my process into the window of an external process using the SetParent ... window of the main application. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c preprocessor - Is there a good reason for always enclosing a define in parentheses in C?

Clearly, there are times where #define statements must have parentheses, like so: #define WIDTH 80+20 int a = WIDTH ... Does such a case exist? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - malloc(sizeof(int)) vs malloc(sizeof(int *)) vs (int *)malloc(sizeof(int))

I acknowledge that all three of these have a different meaning. But, I don't understand on what particular instances ... *)malloc(sizeof(int)) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What is the rationale for fread/fwrite taking size and count as arguments?

We had a discussion here at work regarding why fread() and fwrite() take a size per member and count and return ... short item count (or zero). See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How can a shared library (.so) call a function that is implemented in its loading program?

I have a shared library that I implemented and want the .so to call a function that's implemented in the ... versa which is the common usage. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - how to get hexdump of a structure data

.... finalize(char *hdrs, sendip_data *headers[], int index, sendip_data *data, sendip_data *pack) { ..... ... ..So please suggest me something. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What does tilde(~) operator do?

I recently saw the above operator in a code,I googled for it but found nothing.The code is below.Please describe ... fclose(ft); return 0; } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - atoi vs atol vs strtol vs strtoul vs sscanf

I'm trying to figure out from a command line being parsed, which function would be best to convert either a ... string to an integer for use? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Use of cudamalloc(). Why the double pointer?

I am currently going through the tutorial examples on http://code.google.com/p/stanford-cs193g-sp2010/ to learn ... function does on the CPU? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - I do not understand how execlp() works in Linux

I have spent the last 2 days trying to understand the execlp() system call, but yet here I am. Let me ... confused. Any help is appreciated. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Why are LIB files beasts of such a duplicitous nature?

I'm trying to understand this LIB file business on Microsoft Windows, and I've just made a discovery that will ... extension .ILB (or whatever)? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What does -D_XOPEN_SOURCE do/mean?

I recently encountered some code that gcc would not compile without this arg. I checked the gcc man page, but did ... , but what do those do? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What is the proper #include for the function 'sleep()'?

I am using the Big Nerd Ranch book Objective-C Programming, and it starts out by having us write in C in ... which #include I needed to use! See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Why do I have to define LD_LIBRARY_PATH with an export every time I run my application?

I have some code that uses some shared libraries (c code on gcc). When compiling I have to explicitly ... LD_LIBRARY_PATH="/path/to/library/" See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - GCC fatal error: stdio.h: No such file or directory

I'm trying to compile a program in C on OS X 10.9 with GCC 4.9 (experimental). For some reason, I'm getting ... issue, and how can it be fixed? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - When to use static keyword before global variables?

Can someone explain when you're supposed to use the static keyword before global variables or constants defined ... practices for using static? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Perceptron learning algorithm not converging to 0

Here is my perceptron implementation in ANSI C: #include <stdio.h> #include <stdlib.h> #include <math.h> float ... "PAUSE"); return 0; } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How many GCC optimization levels are there?

How many GCC optimization levels are there? I tried gcc -O1, gcc -O2, gcc -O3, and gcc -O4 If I ... . How many optimization levels are there? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - What is the purpose of the RBP register in x86_64 assembler?

So I'm trying to learn a little bit of assembly, because I need it for Computer Architecture class. I wrote a ... RAM), Intel 64 bit processor See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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