Recent questions tagged C

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c - Getting started with Intel x86 SSE SIMD instructions

I want to learn more about using the SSE. What ways are there to learn, besides the obvious reading the Intel ... GCC X86 Built-in Functions. 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 do I compile the asm generated by GCC?

I'm playing around with some asm code, and something is bothering me. I compile this: #include <stdio.h> int main( ... I make GCC do it for me? 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 difference between fork and thread?

Can anyone explain the difference between a fork and a thread? 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 - The role of #ifdef and #ifndef

#define one 0 #ifdef one printf("one is defined "); #ifndef one printf("one is not defined "); In this what ... #ifndef, and what's the output? 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 one-line function that generates a triangle wave?

In a similar way that modulo generates a sawtooth wave. It doesn't have to be continuous. here is what i ... the equation to quadratic curves. 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 - What exactly does an #if 0 ..... #endif block do?

In C/C++ What happens to code placed between an #if 0/#endif block? #if 0 //Code goes here #endif Does ... and therefore does not get executed? 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 is a CRC32 checksum calculated?

Maybe I'm just not seeing it, but CRC32 seems either needlessly complicated, or insufficiently explained anywhere ... would be very 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 - What do pty and tty mean?

I noticed many mentions of pty and tty in some open source projects, could someone tell me what do they ... is the difference between them? 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 - strtok causing segfault but not when step through code

I am new to C and I am trying to split a date/time string into separate variables. However, when I step ... for any help you can provide. 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 we separately cast to "float" in an integer division?

For example: int number1 = 1, number2= 2; float variable = (float)number1/(float)number2; Instead of this, Why ... = (float)(number1/number2); 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 - Segmentation Fault error in 3D array memory allocation

I have a pointer variable int ***a in C. I'm passing it to a function as &a i.e reference. In the function I'm getting ... i,j,k,a[i][j][k]); } 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 - OpenMP multiple threads update same array

I have the following code in my program and I want to accelerate it using OpenMP. ... for(i=curr_index; ... always a multiple of omp_nthreads. 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 does combining two shifts of a uint8_t produce a different result?

Could someone explain me why: x = x << 1; x = x >> 1; and: x = (x << 1) >> 1; produce ... that? I'd expect these expressions to be equivalent? 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 is this array having all remaining values initialized to zero?

Hello I am a beginner in C programming language, recently i started learning arrays, I have studied that by ... having 0 as default value. 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 - Divisiblity of 5 without using % and / operator

how to check whether a number is divisible by 5 or not without using % and / operator. I want a quickest algorithm for this problem. 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 - AVX scalar operations are much faster

I test the following simple function void mul(double *a, double *b) { for (int i = 0; i<N; i++) a[i] ... /maxbw); _mm_free(a), _mm_free(b); } 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 - Segmentation fault when allocating large arrays on the stack

When I compiled this simple C code it's fine but after uncommenting the line it shows segmentation fault. I don't ... %d",&neigh); 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 - System call hooking example arguments are incorrect

I wrote an example of system call hooking from our Linux Kernel module. Updated open system call in system call ... mistake in the above code? 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 - Macros and postincrement

Here's some more weird macro behavior I was hoping somebody could shed light on: #define MAX(a,b) (a>b?a: ... of why macros should be avoided!) 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 determine integer types that are twice the width as `int` and `unsigned`?

Values of intermediate multiplication typically need twice the number of bits as inputs. // Example int foo(int a ... a great portability test. 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 - Memory Leaks in GTK hello_world program

So... I'm trying to eliminate some memory leaks from my GTK+ 3 program. I though it would be a good idea to ... */ gtk_main (); 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 reset a socket back to blocking mode (after I set it to nonblocking mode)?

I have read this regarding setting a socket to non-blocking mode. http://www.gnu.org/software/libc/manual/ ... a O_BLOCK flag? 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 - Why does GCC not warn for unreachable code?

I wonder why gcc (4.6.3) gives me no warning for the unreachable code in this example: #include <stdio.h ... Wall -Werror should throw an error. 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 - Check if a value exists in an array in Cython

I want to know how to check if a value or a object exists in an array, like in python: a = [1,2,3, ... correct, but it illustrates what I mean. 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 predictable is the result of rand() between individual systems?

I plan to create a challenge which will involve predictable randomness. I understand that for a given ... systems yield different results? 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 - To check the E2BIG error condition in exec

I am writing a small program to test the E2BIG error condition in exec sys call. If the arguments passed exceeds the ... " E2BIG"); break; } } 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 - linux convert time(for different timezones) to UTC

Is there a way, in linux, to programmatically get UTC time for a given time string like Tue Dec 14 10: ... changing) local time zone settings? 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 - Memory latency measurement with time stamp counter

I have written the following code which first flushes two array elements and then tries to read elements in ... results are now meaningful. See Question&Answers more detail:os...

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

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