Recent questions tagged C

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c - How do I open an in-memory database file into sqlite3

I'm on a system with no access to disk. My C program has in memory the contents of a valid, small ... something along those lines? 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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c - fprintf, error: format not a string literal and no format arguments [-Werror=format-security

when I try to compile fprintf(stderr,Usage) on Ubuntu I got this error: error: format not a string literal ... successfully. Anyone has an idea? 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 sort files in some directory by the names on Linux

I use opendir() and readdir() to display the file names in a directory. But they are disordered. How can I sort them? The language is 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 - sscanf doesn't move, scanning same integer everytime

I have a string that has ints and I'm trying to get all the ints into another array. When sscanf fails to ... Any idea what's wrong? 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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c - Embedding Dart into application

I am just experimenting , but want to use Dart as a scripting language for a high performance simulation application ... dart-vm/tree/master/src 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 produce beep sound using "a" escape character?

If I write the following program, then there is no beep sound on running the code. #include <stdio.h> int main ... beep sound using C program ? 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 many 64-bit multiplications are needed to calculate the low 128-bits of a 64-bit by 128-bit product?

Consider that you want to calculate the low 128-bits of the result of multiplying a 64-bit and 128-bit ... hence claim "zero" multiplications). 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 - error: use of undeclared identifier 'errno_t'

Here is my dead simple dummy code: #include <errno.h> int main(void) { errno_t e; return 0; } Which ... standard is specified for the compiler? 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 - Avoiding a fork()/SIGCHLD race condition

Please consider the following fork()/SIGCHLD pseudo-code. // main program excerpt for (;;) { if ( ... please let me know! 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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c - Maximum values for time_t (struct timespec)

I am using the struct timespec structure and here it is: struct timespec { time_t tv_sec; /* Seconds */ long tv_nsec ... not find it in time.h. 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 - Three arguments to main, and other obfuscating tricks

The following obfuscated C code prints the words to the "12 days of Xmas". I was trying to puzzle out how it ... .vpbks,fxntdCeghiry"),a+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 - changing a process's parent

Is it possible to change a process parent? ex: parent A has Child B can I make the parent of B is the Init process without killing A? 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 - add seconds to a date

I need to add seconds to a date. For example, if I have a date such as 2009127000000, I need to add ... 20091231235957. Is this possible in 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 - When a program terminates what happens to the memory allocated using malloc that is not free'ed?

Say I have the following program #include <stdio.h> #include <stdlib.h> int main(void) { int * i; if ( ... of this code during its termination? 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 - Converting a non-`void` pointer to `uintptr_t` and vice-versa

There are two related C standard rules: C99 standard, 6.3.2.3: A pointer to void may be converted ... my question is about standard compliance) 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 - __STDC_LIB_EXT1__ availability in gcc and clang

Since a quick Google search did not find anything, I will try to ask here (since many people involved in ... set is simply poorly supported? 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 Android POSIX-compatible?

Is Android POSIX-compatible? I know it uses the Linux kernel, but I'm not sure if that means it's ... Android without needing any code-changes? 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 - Header alloca.h in Windows

I can't see any alloca.h equivalent in Visual C 2010. How can one perform stack allocation in Visual C on Windows? I miss the function alloca. 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 preprocessor - C++ assert: the precedence of the expression in an assert macro

In C++: assert( std::is_same<int , int>::value ); // does not compile assert( (std::is_same<int , int ... ); // compiles Can anyone explain why? 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 - Change process name in Linux

I'm on Linux and I am forking/execing a new process out of my C spawn application. Is it possible to also ... they all have the same name. See Question&Answers more detail:os...

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

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635 views

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c - Casting function returns to void

Many times I see in open source code that a call to a C function is cast to void. For example, in the source ... ""); Why is this good practice? 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 reset static variables within a function

Is there a way to reset variables declared as static within a function? The goal is to make sure that the function ... ; } //do other things } See Question&Answers more detail:os...

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

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749 views

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c - Quick way to override -Werror flag?

If cc configuration is set to use -Werror is there a way to override -Werror flag from the terminal when using make? 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 I still access a member of a struct after the pointer to it is freed?

If I define a structure... struct LinkNode { int node_val; struct LinkNode *next_node; }; and then create ... how the underlying process works. 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 explicitly clearing/zeroing sensitive variables after use sensible?

I have noticed some programs explicitly zero sensitive memory allocations after use. For example, OpenSSL has a method ... of the first program? See Question&Answers more detail:os...

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

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528 views

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c - Make gcc use conditional moves

Is there a gcc pragma or something I can use to force gcc to generate branch-free instructions on a specific ... of the versions gcc produces. See Question&Answers more detail:os...

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

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706 views

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c - Set a timeout for reading stdin

Is there a way to timeout a reading from stdin in order for the program not to hang for too long ? read(0, var, numberofbytes); See Question&Answers more detail:os...

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

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511 views

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c - subnormal IEEE 754 floating point numbers support on iOS ARM devices (iPhone 4)

While porting an application from Linux x86 to iOS ARM (iPhone 4), I've discovered a difference in behavior ... floating point code ? 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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