Recent questions tagged C

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c - How to signal select() to return immediately?

I have a worker thread that is listening to a TCP socket for incoming traffic, and buffering the received data ... wrap it, if necessary. 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 place a variable at a given absolute address in memory (with GCC)

The RealView ARM C Compiler supports placing a variable at a given memory address using the variable attribute ... a similar variable attribute? 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 - x86_64 ASM - maximum bytes for an instruction?

What is the maximum number of bytes a complete instruction would require in x64 asm code? Something like a jump ... a x64 instruction can 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 - Does readdir() guarantee an order?

I'm getting a list of files on a linux-like system using opendir/readdir. It appears that the directory ... not readdir guarrantees an order? 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 - Accessing elements of a matrix row-wise versus column-wise

A matrix A[i][j] is given. If we want to add the elements of the matrix, which method is better and why ... takes equal time, does it matter? 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 generate random numbers in parallel?

I want to generate pseudorandom numbers in parallel using openMP, something like this: int i; #pragma omp parallel ... that this idea is good. 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 turn a hex string into an unsigned char array?

For example, I have a cstring "E8 48 D8 FF FF 8B 0D" (including spaces) which needs to be converted into the ... this a C question. I'm sorry! 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 sizeof(array) works at runtime?

I have read that sizeof operator in C is interpreted at compile time and since at compile time compiler knows the ... is it working properly ? 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 argv[n] writable?

C11 5.1.2.2.1/2 says: The parameters argc and argv and the strings pointed to by the argv array ... should assume they are modifiable objects. 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 - Multiple definition of ... linker error

I defined a special file: config.h My project also has files: t.c, t.h pp.c, pp.h b.c b.h l.cpp ... use in my project. Any help solving 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 - Complex declarations

How do I interpret complex declarations like: int * (* (*fp1) (int) ) [10]; ---> declaration ... followed to understand the above declarations? 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 - Finding all the unique permutations of a string without generating duplicates

Finding all the permutations of a string is by a well known Steinhaus-Johnson-Trotter algorithm. But if the ... In the most efficient way) 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 getch() and getchar()?

What is the exact difference between the getch and getchar 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 - Compute fast log base 2 ceiling

What is a fast way to compute the (long int) ceiling(log_2(i)), where the input and output are 64- ... ://stackoverflow.com/a/51351885/365478 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 - Getting absolute path of a file

How can I convert a relative path to an absolute path in C on Unix? Is there a convenient system function ... find something similar on Unix... 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 - Print TCP Packet Data

In TCP Communication, when the packet is being transferred from ethernet to network(IP) layer, I want to print ... these coding is being done? 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 fscanf() vs. fgets() and sscanf()

In the book Practical C Programming, I find that the combination of fgets() and sscanf() is used to read ... some hidden quirk I'm missing? 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 - Fastest Implementation of the Natural Exponential Function Using SSE

I'm looking for an approximation of the natural exponential function operating on SSE element. Namely - __m128 exp( ... C Style. 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 - Using intptr_t instead of void*?

Is it a good idea to use intptr_t as a general-purpose storage (to hold pointers and integer values) ... should I take into consideration? 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 one's complement a real-world issue, or just a historical one?

Another question asked about determining odd/evenness in C, and the idiomatic (x & 1) approach was correctly flagged ... and punch cards...? 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 memset take an int instead of a char?

Why does memset take an int as the second argument instead of a char, whereas wmemset takes a wchar_t instead of ... like long or long long? 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 - Determine word size of my processor

How do I determine the word size of my CPU? If I understand correct an int should be one word right? I'm ... the word size of my 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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c - initializing an array of ints

Does anyone have a way to initialize an array of ints (any multi-byte type is fine really), to a non-zero ... solution. (other libs are fine) 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 - "int *nums = {5, 2, 1, 4}" causes a segmentation fault

int *nums = {5, 2, 1, 4}; printf("%d ", nums[0]); causes a segfault, whereas int nums[] = {5 ... why array initializers work the way they 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 - How to get network adapter stats in linux/Mac OSX?

I'm looking for a way to get hold of network stats in C on Linux and MacOSX. Specifically, I need to ... Any help would be much 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 use an asterisk "[*]" instead of an integer for a VLA array parameter of a function?

When using variable-Length Array as parameter in function int sum(int n, int a[n]); it is easy to understand ... used instead of n inside []? 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 - difference between <stdlib.h> and <malloc.h>

When I use malloc in a C program, I get a warning: warning: incompatible implicit declaration of built-in function ' ... bit with gcc 4.6.3) 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 - CPU TSC fetch operation especially in multicore-multi-processor environment

In Linux world, to get nano seconds precision timer/clockticks one can use : #include <sys/time.h> int ... sync across cores and processors. See Question&Answers more detail:os...

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

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