Recent questions tagged C

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c - Is there a difference between initializing a variable and assigning it a value immediately after declaration?

Assuming a purely non-optimizing compiler, is there any difference in machine code between initializing a variable and ... was left in memory? 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 a big integer to decimal string

At the risk of having this question voted as a duplicate, or even to have it closed, I had this question has ... and the other for the divisor. 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 - Using fork(), how can I make child process run always first?

Child and parent process execution is parallel and which starts first depends on OS scheduling. But what can be ... should be in sequence. 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 - Take screenshot of desktop when Windows is locked (Win+L)

I want to take a screenshot of desktop while Windows is locked (with Win+L). Standard methods make a black ... a useful image. Any ideas? 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 - Designing a monitor process for monitoring and restarting processes

I am designing a monitor process. The job of the monitor process is to monitor a few set of configured ... achieving my requirement? Regards. 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 - Detecting file deletion after fopen

im working in a code that detects changes in a file (a log file) then its process the changes with the help of ... but how i can do 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 - How can I apply __attribute__(( aligned(32))) to an int *?

In my program I need to apply __attribute__(( aligned(32))) to an int * or float * I tried like this but ... this but didn't find the answer 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 - ungetc: number of bytes of pushback

ungetc is only guaranteed to take one byte of pushback. On the other hand, I've tested it on Windows and ... it actually only takes one byte? 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 assembly strictly required to make the "lowest" part of an operating system?

Im a mid-level(abstraction) programmer, and some months ago i started to think if i should reduce or increase ... ..) Thanks for your support 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 - Dot Product of Vectors with SIMD

I am attempting to use SIMD instructions to speed up a dot product calculation in my C code. However, the run times ... you all for your 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 standard input buffer?

#include <stdio.h> int main(void) { int c; c = getchar(); putchar(c); c = getchar(); putchar(c); c ... it. Can you advise me some resources? 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 - floating point numbers equality checking

With the following code, #include <stdio.h> int main(void){ float x; x=(float)3.3==3.3; printf("%f", ... Why is there a difference in output? 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 - memcpy for multidimensional array

Is there a way we can copy every element from one multidimensional array to another multidimensional array by just doing ... //not printing 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 - Ncurses and Linux pipeline

I'd like to write a simple program using ncurses for displaying some data. I would then like for the program ... and ncurses at the same time? 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 - Modifying a const variable with the volatile keyword

I was answering a question and made this test program. #include <stdio.h> int main() { volatile const int v = ... shed some light on the issue. 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 - Do I need to initiallize(set to 0) memory after calling realloc?

I need to implement a simple dynamic array of pointers to a typedef'ed pointer. Using realloc each time it's requested ... free(a); 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 - Is there a way to determine a member offset at compile time?

I'm finding I'm spending a lot of time trying to determine member offsets of structures while debugging. I was ... of gcc to compile C 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 - How to enable sse3 autovectorization in gcc

I have a simple loop with takes the product of n complex numbers. As I perform this loop millions of times I ... .note.GNU-stack,"",@progbits 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 indicate that the memory *pointed* to by an inline ASM argument may be used?

Consider the following small function: void foo(int* iptr) { iptr[10] = 1; __asm__ volatile ("nop"::"r"( ... and anything it can point to? 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 it legal to assign a restricted pointer to another pointer, and use the second pointer to modify the value?

Does the following method respect the "restrict" contract? void fun(int* restrict foo) { int* bar = foo + ... , but I need some clarification. 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 fix gcc error: expected while before void

So I am writing a peer-to-peer chat client that uses pthreads to manage all the IO and when I compile the file gcc ... (PROMPT); } 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 - how to use correctly fork() and exec()

I have this code; pid_t process; process = fork(); if (process < 0){ //fork error perror("fork"); exit ... problem in this part of code. 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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864 views

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c - Unexpected sign extension of int32 or 32bit pointer when converted to uint64

I compiled this code using Visual Studio 2010 (cl.exe /W4) as a C file: int main( int argc, char *argv[ ... value of a given type of expression. 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 - Create image from unsigned char buffer

I'm capturing fingerprints using a device called Secugen Pro 20, it has its own SDK for Linux, and i want to capture the ... . OBS: I'm new to 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 - How can I monitor status changes of windows services under windows xp?

I'm trying to write a program in C, that can detect when some Windows services (aka. NT services) are ... like to stay away from scripting. See Question&Answers more detail:os...

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

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651 views

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c - Building backward compatible binaries with newer CPU instructions support

What is the best way to implement multiple versions of the same function that uses a specific CPU instructions if ... an if/else every time? See Question&Answers more detail:os...

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

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890 views

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c - Create pthread with the function of multiple arguments

If I am going to create a pthread for the following function. Assume everything is properly delared. pthread_create(&threadId, ... a; d = b; } See Question&Answers more detail:os...

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

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918 views

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c - Faster than rand()?

I'm working on an algorithm which needs to generate millions of numbers as fast as possible. Actually I ... the-intel-pentiumr-4-processor/ See Question&Answers more detail:os...

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

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