Recent questions tagged C

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c - does openmp allocate memory and free all after

Does openmp allocate memory and free all memory? Because I ran valgrind, and did free all my lists.. Everything that I malloc ... ============== 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 isn't the result of this cast an lvalue?

I need some advice with this strange behavior - lets have this code: int ** p; This compiles without any ... is wrong with the second example? 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 do i get the same value of the address?

#include<stdio.h> #include<conio.h> void vaibhav() { int a; printf("%u ",&a); } int main() { vaibhav(); ... dependent? I am using dev c++ ide. 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 - -SIGCONT does not continue paused process?

The following process does not continue after running kill -SIGCONT pid from another terminal. #include <stdio.h> int ... 't work as expected? 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 - Call function without parameter and parenthesis

In the following code snippet, the main function calls foo function without any parameter and parenthesis. It is strange ... 0x0(%rax,%rax,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 - Code blocks between #if 0 and #endif must have paired double quotes?

int main(void) { #if 0 something" #endif return 0; } A simple program above generates a warning: missing ... tokens that are treating specially? 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 - About catching the SIGSEGV in multithreaded environment

I'd like to know if it is possible/the recommended way to catch the SIGSEGV signal in multithreaded environment. I ... the raiser's thread id. 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 - SIGIO arriving for file descriptors I did not set it for and when no IO is possible

I am trying to receive a signal when I/O is possible on a file descriptor. The program needs to be doing something else ... ; } } } 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 - Why 2nd scanf doesn't work in my program?

scanf("%d %c",&size,&chara); works but separate scanf for character input does not work. I show these inside the code. ... ); printf(" "); } } 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 is SCHAR_MIN defined as -127 in C99?

§5.2.4.2.1 of C99 defines SCHAR_MIN as -127 and SCHAR_MAX as 127. Should not the range for an 8 bit signed ... was defined -127 and not -128 ? 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 maximum size of buffers memcpy/memset etc. can handle?

What is the maximum size of buffers memcpy and other functions can handle? Is this implementation dependent? Is this ... in as an argument? 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 convert 32-bit float to 8-bit signed char? (4:1 packing of int32 to int8 __m256i)

What I want to do is: Multiply the input floating point number by a fixed factor. Convert them to 8-bit signed ... welcome, thank you so much! 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 can't I edit a char in a char*?

Below is an exceedingly simple example. It compiles fine using gcc on Mac OS X (Snow Leopard). At runtime it outputs Bus ... "; a[0] = '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 - Why no output on console on signal handling?

I was trying this program from Advance Programming in Unix Environment. #include<stdio.h> #include<signal.h ... any practical application. 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 - invalid conversion from 'void*' to 'node*' [-fpermissive]

I have a C program that produces an error: invalid conversion from 'void*' to 'node*' [-fpermissive] Here's my ... ; } What am I doing 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 - Does Ruby's Enumerable#zip create arrays internally?

In Ruby - Compare two Enumerators elegantly, it was said The problem with zip is that it creates arrays internally, ... (Qnil)? return result; } 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 - #Define VS Variable

I cannot understand what is the difference between: #define WIDTH 10 and int width = 10; What are the benefits of using the first or the second? 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 - Compiler optimization causing program to run slower

I have the following piece of code that I wrote in C. Its fairly simple as it just right bit-shifts x for ... on what might be causing 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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c - Is it possible to keep an entire array in cpu register

In below code, int main( ) { register int arr[4]; /* ... */ } Is it possible that 'arr' is ... will ignore register storage class for array. 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 - KMALLOC size allocation

Does KMALLOC allocates only in page size memory or it can allocate less ? What are the sizes that the kmalloc can ... the cache that is ready ? See Question&Answers more detail:os...

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

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433 views

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c - What is the `pthread_mutex_lock()` wake order with multiple threads waiting?

Suppose I have multiple threads blocking on a call to pthread_mutex_lock(). When the mutex becomes available, does the ... are they in? 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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406 views

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c - Updating pointers in a function

I am passing a pointer a function that updates it. However when the function returns the pointer it returns to the ... to figure it out :-) See Question&Answers more detail:os...

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

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429 views

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c - Is integer overflow undefined in inline x86 assembly?

Say I have the following C code: int32_t foo(int32_t x) { return x + 1; } This is undefined behavior when ... only apply to the 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 - Is `memcpy((void *)dest, src, n)` with a `volatile` array safe?

I have a buffer that I use for UART, which is declared this way: union Eusart_Buff { uint8_t b8[16]; ... , and therefore this issue disappears. 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 create a process on Mac OS using fork() and exec()

I am working on a relatively simple, independent "process starter" that I would like to get to work on Windows ( ... would come up. Thank you! See Question&Answers more detail:os...

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

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359 views

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c - GCC compiles leading zero count poorly unless Haswell specified

GCC supports the __builtin_clz(int x) builtin, which counts the number of number of leading zeros (consecutive most- ... + 1 in twos-complement. 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 - Does fseek() move the file pointer to the beginning of the file if it was opened in "a+b" mode?

I wish to open a file using the "a+b" mode, i.e. if it does not exist it is created automatically, but ... or I am using the wrong keywords). See Question&Answers more detail:os...

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

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549 views

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c - check if carry flag is set

Using inline assembler [gcc, intel, c], how to check if the carry flag is set after an operation? See Question&Answers more detail:os...

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

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