Recent questions tagged C

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c - How to avoid -nan(ind) error when using the pow function. Is it possible to use pow with negative bases with non-integral exponents

I get an error when using the pow function -nan(ind) prints to the screen. Wondering if theres a way to use pow ... printf("%lf ", sum); } } 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 - call to undefined function in function main()

whenever i use a function which is called in main function, it gives this error: Call to undefined function in function main( ... "%d ", m ) ; } 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 - Default value to non initialized variables

I'm reading this tutorial about debugging. I pasted the factorial code in my .c archive: #include <stdio.h> ... , instead of a garbage 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 - Invalid read/write sometimes creates segmentation fault and sometimes does not

Example code: int main () { char b[] = {"abcd"}; char *c = NULL; printf(" size: %d ",sizeof(b)); ... write and sometimes do not get a core dump? 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 - When will strcmp not return -1, 0 or 1?

From the man page: The strcmp() and strncmp() functions return an integer less than, equal to, or greater ... documented behavior is bad style. 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 - Recursive Fib with Threads, Segmentation Fault?

Any ideas why it works fine for values like 0, 1, 2, 3, 4... and seg faults for values like > ... ; return returnMinusOne + returnMinustwo; } } 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 - Pass unsigned char pointer to atoi without cast

On some embedded device, I have passed an unsigned char pointer to atoi without a cast. unsigned char c[10]= ... also ok to unsigned char? 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 - Validate parameter for 0 or 1

I have a parameter num of int type, where the user can give it one of two values: 0 or 1. I can check ... faster way to run this check. Thanks 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 - strcmp behaviour in 32-bit and 64-bit systems

The following piece of code behaves differently in 32-bit and 64-bit operating systems. char *cat = "v,a"; if ... 64-bit OS are Linux (Fedora). 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 - Variable changed in function not seen by caller?

Yes, I know it sounds silly but i have no idea what i'm doing wrong! The function is part of a poker game, in ... (c2)); px = 8; } } 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 open make my file descriptor 0?

I'm working on a program that is using a pipe and forks and need to change the write end to an output file. But ... is 0? Or how to fix it? 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 are declarations put between func() and {}?

In sed source I saw often func(...) int b; char c; { ... } Why put variables there? Does it ... 57 reg_errcode_t ret; 58 int init_buf_len; 59 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 - rand() not generating random numbers after modulo operation

I'm taking a C refresher and took on a board game as an exercise. The board game is "Game of the Generals" ... ,rand_x,rand_y); } } } } 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 - Can GCC merge duplicate global string arrays?

I've been wondering if it's possible to compile using GCC with some optimization flag to avoid have two ... uses the same memory addresses? 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 - Writing to both stdout & a file

I have a parent process which forks out a child to perform execv(). I need the output given by execv() to ... file, without using pipes or tees? See Question&Answers more detail:os...

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

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317 views

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c - Find the minimum number in an array with recursion?

int i = 0; int min = x[i]; while ( i < n ){ if ( x[i] < min ){ min = x[i]; } i++ ... like to write a function that with recursion. Please help! See Question&Answers more detail:os...

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

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257 views

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c - Code alignment in one object file is affecting the performance of a function in another object file

I'm familiar with data alignment and performance but I'm rather new to aligning code. I started programming in x86-64 ... 5e: c3 ret 5f: 90 nop See Question&Answers more detail:os...

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

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420 views

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c - Char array initialization dilemma

Consider following code: // hacky, since "123" is 4 chars long (including terminating 0) char symbols[3] ... explicitly defined in C standard. See Question&Answers more detail:os...

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

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576 views

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c - warning: comparison of unsigned expression >= 0 is always true

I have the following error when compiling a C file: t_memmove.c: In function ft_memmove': ft_memmove.c:19: ... does this error come up? See Question&Answers more detail:os...

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

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342 views

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c - Return value from writing an unused parameter when falling off the end of a non-void function

In this golfing answer I saw a trick where the return value is the second parameter which is not passed in. ... of different versions of GCC. See Question&Answers more detail:os...

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

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411 views

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c - 2D Array indexing - undefined behavior?

I've recently got into some pieces of code doing some questionable 2D arrays indexing operations. Considering ... to undefined behavior? See Question&Answers more detail:os...

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

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318 views

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c - Compiler changes printf to puts

Consider the following code: #include <stdio.h> void foo() { printf("Hello world "); } void bar() { ... there is another explanation of 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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418 views

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c - When can the parentheses around arguments in macros be omitted?

Often and often I felt some of the parentheses around arguments in macro definitions were redundant. It's too ... ! Parenthesize them all! TnT See Question&Answers more detail:os...

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

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437 views

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c - Undefined reference to t1sl_steup_key_block when linking OpenSSL

I got a problem of linking an OpenSSL library into an existing project. Where I do get it wrong? ... undefined reference to `EVP_idea_cbc' See Question&Answers more detail:os...

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

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708 views

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c - right shift count >= width of type or left shift count >= width of type

I am new to bits, I am trying to get 64 bit value send using UDP. int plugin(unsigned char *Buffer) { ... ? Please suggest me a way forward. See Question&Answers more detail:os...

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

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323 views

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c - Assignment statement used in conditional operators

Can anybody please tell me why this statement is giving an error - Lvalue Required (a>b?g=a:g=b); but ... b are taken as input from keyboard. See Question&Answers more detail:os...

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

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341 views

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c - Multiply two overflowing integers modulo a third

Given three integers, a, band c with a,b <= c < INT_MAX I need to compute (a * b) % c but a * ... won't overflow for the values in question? See Question&Answers more detail:os...

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

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384 views

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c - Assigning a pointer to an integer

Can I assign a pointer to an integer variable? Like the following. int *pointer; int array1[25]; int ... possible to do like 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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