Recent questions tagged C

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c - Cache misses when accessing an array in nested loop

So I have this question from my professor, and I can not figure out why vector2 is faster and has less cache ... cache lines in to this either. 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 - Intrinsics for 128 multiplication and division

In x86_64 I know that the mul and div opp codes support 128 integers by putting the lower 64 bits in the rax ... h header instead of inline asm. 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 - Radix Sort Base 16 (Hexadecimals)

I have spent more 10hr+ on trying to sort the following(hexadecimals) in LSD radix sort, but no avail. There ... of them covers the details. 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 - Reaping zombie process - child

I am taking command line arguments to main from parent to child and counting them and printing. My question is that i am ... n); } exit(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 - Converting bytes array to integer

I have a 4-byte array (data) of type uint8_t, which represents a speed data integer. I'm trying to cast this ... speed*10; data=(uint8_t*)speed; 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 - Matlab 2013b generated code produces Undefined symbols for architecture x86_64 error in mex

I have a C-Code generated by the Simulink Coder that I need to use in a C S-function. This may sound a bit ... ? Thanks a lot for the 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 - How to make malloc return the same address every time using MSVC?

For debugging purposes, I would like malloc to return the same addresses every time the program is executed, however ... but it does not work. 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 I ask OpenMP to create threads only once at each run of the program?

I am trying to parallelize a large program that is written by a third-party. I cannot disclose the code, ... be highly 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 - read() only reads a few bytes from file

I wanted to read the content of a file using the read() function. I tried the following: #define BUFFER_LENGTH ... correct in the source 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 - Type casting: double to char: multiple questions

Consider this code: #include <stdio.h> int main(void) { /* TEST 1 */ double d = 128; char ch = (char)d; ... ? Where these 0 and -2 come from? 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 - Stray "303" and stray "215" in program -- why?

Instead of stray "302" in program for which I found here, I got the error message: algo.c:118: error: stray ... delete or correct it. Good luck! 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 'cat' in following simple device read program

static ssize_t device_read (struct file* filp, char *bufStoreData, size_t bufCount, loff_t* curOffset) { printk ... this basic concept. 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 - NUL undeclared- first use in this function

From the web I understand that C contains NUL keyword. But while compiling I get an error NUL undeclared first use ... why I get this error? 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 difference between "rb+" and "ab" in fopen()?

I do not understand the difference between the "ab" and "rb+" modes when using fopen() in C. Why would I choose one instead of the other? 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 - Passing address of array as a function parameter

Recently, I was debugging one of my programs and found a mistake that I've constantly make, but it was not shown ... this is a valid syntax } 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 libc provide functions with two names?

Before the advent of direct binding (-B direct) libc provided many functions with two names. For example, ... the same code twice though. 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 doesn't this code cause a segfault?

Why doesn't this segfault? #include <stdio.h> int main() { int i; int arr[] = {1, 2, 3, 4}; for(i ... I am trying it on 32 bit crunchbang linux 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 - Flushing fopen()'ed files opened in update mode,between read and write operations.Explicit flushing needed?

I have read this about the switch between read and write operations(and vice-versa) for files opened for update ... has reached end-of-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 - strange result on macro expansion

Consider the following code snippet #include<stdio.h> #define A -B #define B -C #define C 5 int main() { printf ... lvalue required. Isn't 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 - Using gcc, I am unable to get 3rd party library, Cairo, to link/compile

The errors that show up are for undefined symbols, not the Cairo functions I copied from the example, but ... be greatly 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 - inotify missing events

I want to monitor USB-Keys on my system. I know they are always mounted in /media so I use inotify to monitor ... Any ideas what's going 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 - Currying/binding with ISO C99

Say I want to implement a numerical integration routine with plain C. That will look something like this: ... C without breaking something? 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 - size of executable files?

I created a very small code to add two integers and save the result in another variables, both in assembly language ... for C code I wrote? 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 - Multiple threads writing on same file

I would like to know if we can use multiple threads to write binary data on the same file. FILE *fd = openfile( ... in the same file. 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 - What does this #define syntax mean?

I came across this one, don't understand. #define IDEBUG(a...) What does the "(a...)" mean? 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 up to the programmer to deallocate on exit()?

I have a program and when I input wrong data from the keyboard it just exits with exit(1). I was testing with ... OS going to take care 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 - Is casting to pointers to pointers to void always safe?

#include <stdio.h> void swap(void *v[], int i, int j) { void *tmp; tmp = v[i]; v[i] = v[j]; v[j ... safe, or if there is any way to replace 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 - Calling SHGetSetSettings from Delphi

I just read this question and this question, and since then I have been trying to call SHGetSetSettings in ... some clarity into all 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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