Recent questions tagged C

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How to be sure what is end of an AT command send to GSM module? I need some character or string that ... the beginning of AT command response? 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 - pthread_cond_wait and pthread_mutex_lock priority?

I have a multiple read threads and one write thread. If I lock mutex on one of the read threads and ... ); pthread_cond_wait(&cond, &mutex); 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 - ioctl giving Invalid Argument

I want to send a opened file descriptor between two different programs. So I am using ioctl with named pipes to do ... ioctl. But it is not. 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 does the program return with an exit code other than I specified?

This is a simple program : int main() { return 0; } The exit code is 0. If I write: int main() { ... 188 instead of 700 the exit code here? 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 top-level volatile or restrict significant in a function prototype?

Is there any practical difference between the following prototypes? void f(const int *p); void f(const int * ... a; ? (Related question) 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 Can I Use Besides usleep in a Modern POSIX Environment?

I'm fairly new to C but writing a small multithreaded application. I want to introduce a delay to a thread. ... the text of the question. 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 - -Wmissing-field-initializer when using designated initializers

I'm using GCC 4.6.2 (Mingw) and compiling with -Wextra. I'm getting strange warnings whenever I use designated ... or is it a compiler bug? 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 variable-length structures between MPI processes

I need to MPI_Gatherv() a number of int/string pairs. Let's say each pair looks like this: struct Pair ... an appropriate MPI datatype for Pair? 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 weird function definition mean?

I came across this C program in a blog post: main() { int n; n = 151; f(n); } f(x) ... explain what this weird function definition means? 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 fseek to backtrack

Is using fseek to backtrack character fscanf operations reliable? Like for example if I have just fscanf-ed 10 ... using fopen in text mode See Question&Answers more detail:os...

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

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553 views

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c - libxml xmlNodePtr to raw xml string?

Given a valid, arbitrary xmlNodePtr, I would like the string representation of that node, including the tag, ... color scheme at xmlsoft.org 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 - Enumeration object set to a value not equal to any of its respective enumeration constants

What value does an enumeration object have if it is set to a value not equal to any of its respective ... standard explicit about the outcome? 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 - Test if preprocessor symbol is defined inside macro

The usual way to test whether a preprocessor symbol is defined is using #ifdef. However, #ifdef cannot be used ... checked is known in advance. 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 lifetime of compound literals passed as arguments?

This compiles without warnings using clang. typedef struct { int option; int value; } someType; someType *init( ... of the compound literal? See Question&Answers more detail:os...

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

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547 views

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c - How to make a file descriptor blocking?

Given an arbitrary file descriptor, can I make it blocking if it is non-blocking? If so, how? See Question&Answers more detail:os...

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

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491 views

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c - Why does frexp() not yield scientific notation?

Scientific notation is the common way to express a number with an explicit order of magnitude. First a ... another floating-point 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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574 views

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c - How does realloc know how much to copy?

how does realloc know the size of original data? void *realloc(void *ptr, size_t size); So, if the implementation ... code with malloc/free/..? 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 are the file permissions changed when creating a file with the open system call on Linux?

I am creating a file with full permission (777) using the open system call, but when I do ls -l I can see ... ubuntu 0 2012-09-19 11:55 test See Question&Answers more detail:os...

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

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491 views

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c - Modular Exponentiation

In C/C++ how can I calculate (a^b)%m where b does not fit into 64 bits? In other words, is there a way of ... (b)) time or O(log(b%m)) time? 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 - AT command responses (understanding order of code execution on Arduino)

I'm sending AT commands to an ESP8266 from an Arduino Uno/Nano (ATmega328) and attempting to parse the end of the strings ... . "OK" or "OK "). See Question&Answers more detail:os...

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

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467 views

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c - fgets prompt limited to 1024 Bytes

I have been struggling with a pretty simple issue writing a little program in C. Getting input (commands, ... _SC_LINE_MAX (2048) bytes/chars? See Question&Answers more detail:os...

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

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374 views

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c - main() function defined without return type gives warning

This is my program: main() { printf("hello world "); } I get this warning when compiling it: function ... warning disappears. Why is that so? 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 - Variably modified 'variable_name' at file scope error?

New to C. I'm getting the following error when compiling: error: variably modified 'header' at file scope error: ... header; and char header[]; See Question&Answers more detail:os...

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

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529 views

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c - strcpy : Implementation method

I was going through a possible implementation method for library function strcpy. It is : void strcpy(char *src, char ... without check of '' ?? 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 speed up this problem by MPI

(1). I am wondering how I can speed up the time-consuming computation in the loop of my code below using ... answer my other questions. 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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609 views

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c - Cross-compiling of kernel module for ARM architecture

I'm trying to make a .ko file for ARM from a linux x86 machine. I tried the following Makefile: 1 obj-m += ... ] Error 2 What did I do 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 - Is there a Windows variant of strsep() function?

I'm trying to parse a delimited string that has some empty parameters. Example: "|One|two|three||octopus|garbagecan| ... handle this if I can. 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 - fgetc(stdin) in a loop is producing strange behaviour

I have this code while(1){ printf("hello world ! "); fgetc(stdin); } when this runs and I enter a letter ... behaviour, 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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