Recent questions tagged C

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c - Does the pointer passed to free() have to point to beginning of the memory block, or can it point to the interior?

The question is in the title... I searched but couldn't find anything. Edit: I don't really see any need to ... the pointer given to it is 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 - Best assembly or compilation for minimum of three values

I'm looking at code generated by GCC-4.8 for x86_64 and wondering if there is a better (faster) way to compute ... bad-idea-on-out-of-order-cpus 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 - Signed & unsigned integer multiplication

In fixed point math I use a lot of 16bit signals and perform multiplication with 32bit intermediate results. For ... Or can this work nicely? 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 - Looping with an unsigned char

What is an elegant way of executing something similar to this without entering an infinite loop, if i must be an unsigned ... ("%d ", i); } 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 does this generate a segmentation fault?

#include<stdio.h> void foo(int **arr) { arr[1][1]++; } main() { int arr[20][20]; printf("%d ",arr[1][1]); ... )arr); printf("%d ",arr[1][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 - What is the use of ignoring `SIGCHLD` signal with `sigaction(2)`?

It turns out that we can prevent appearing of a zombie process (i.e. the one whose parent doesn't wait() for ... ; //parent process 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 preprocessor - Detect presence or absence of arguments in a C macro

How can one define a C macro IFARGS(YES, NO, ...) such that invoking IFARGS with no additional arguments ... a proof of its impossibility). 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 signal handler goes to infinite loop? - SIGSEGV

Any idea why the signal handler goes to infinite loop? Here is the code. Please help me. enter code here ... "); 48 puts(mallocPtr); 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 - Can I use strtok() in a Linux Kernel Module?

I need to do a parse on the data written to my module, and the use of the strtok() function of string. ... write my own strtok function? Thanks 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 - Looking for a good explanation of the table generation macro idiom

I want to make this clear up front : I know how this trick works, what I want is a link to a clear explanation to ... on SO, that'd be fine...) 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 solve: sending UDP packet using Sendto() got "message too long"

I want to use the sendto() API to send video and audio data through UDP packet. The sending buffer size I got ... fail! "); return 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 - Macro Expansion

Basic question #define A 5 #define B 10 #define C (A*B) int var; var = C; so here how macros will be ... it will evaluate the result and post 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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490 views

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c - A tested implementation of Peterson Lock algorithm?

Does anyone know of a good/correct implementation of Peterson's Lock algorithm in C? I can't seem to find this. Thanks. See Question&Answers more detail:os...

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

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817 views

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c - How to include math.h #include <math.h> on kernel source file?

I am trying to include math.h in my Linux kernel module. If I use, #include '/usr/include/math.h' It ... such file or directory Why is 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 - freeing the string allocated in strdup() from flex/bison

I have flex code that copies a string lexeme using strdup(). %{ #include "json.tab.h" #define YY_DECL extern "C" ... { int ival; char *sval; } 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 do you use atoi to assign individual elements of a char array?

So as we all probably know, the atoi converts a char to a number. But, what do you do if you only want one ... char array to an int using atoi? See Question&Answers more detail:os...

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

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678 views

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c - Redirect stdout to a file

I am trying to do the equivalent of the bash command ls>foo.txt in C. The code bellow redirects the output to a ... the output of ls to foo.txt? See Question&Answers more detail:os...

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

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565 views

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c - Variable Length Array

I would like to know how a variable length array is managed (what extra variables or data structures are kept on ... arrays). Thanks a lot. 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 stop GCC from breaking my NEON intrinsics?

I need to write optimized NEON code for a project and I'm perfectly happy to write assembly language, but for ... or even ARM's compilers. 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 does RunDll32 work?

How exactly does RunDll32 call a function, without knowing the number/types of arguments that the function can take? ... something of the sort? See Question&Answers more detail:os...

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

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736 views

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c - why does malloc(sizeof(pointer)) work?

This following code works fine: #include <stdio.h> #include <stdlib.h> int main() { struct node{ int a, b, c ... of the line works fine. Why? See Question&Answers more detail:os...

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

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633 views

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c - unsigned becomes signed in if-statement comparisons?

I have searched this site for an answer and found many responses to unsigned/signed comparison but this problem is ... -statement works as well? See Question&Answers more detail:os...

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

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468 views

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c - Determine regular expression's specificity

Given the following regular expressions: - alice@[a-z]+.[a-z]+ - [a-z]+@[a-z]+.[a-z]+ - .* The ... could help me out here... Thanks !! Paul 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 - K&R - Understanding exercise 2-8: Exactly what is asked here?

I'm working through the exercises in the K&R book. Currently I'm stuck at exercise 2-8, which is says ... helpful answer is appreciated. Thanks. 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 use of pragma code section and data section?

What exactly will happen to the data segment and text segment if I use the below two lines in my c ... #pragma DATA_SECTION(globalvar1, "Sec2") See Question&Answers more detail:os...

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

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620 views

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c - Use scanf with Regular Expressions

I've been trying to use regular expressions on scanf, in order to read a string of maximum n characters and ... instead? Thanks in Advance :D See Question&Answers more detail:os...

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

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567 views

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c - what is value- and reference semantics and the difference

What is value semantics and reference semantics and what is the difference between them? Can you please show ... - and value semantics? See Question&Answers more detail:os...

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

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500 views

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c - sqrt, perfect squares and floating point errors

In the sqrt function of most languages (though here I'm mostly interested in C and Haskell), are there any ... the original number? Thank you! See Question&Answers more detail:os...

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

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