Recent questions tagged c

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c - What is the best alternative to strncpy()?

The function strncpy() doesn't always null terminate so I want to know what is the best alternative that always null ... sizeof(buf)-1] = 0; 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 I append to a preprocessor macro?

Is there any way in standard C-or with GNU extensions-to append stuff to a macro definition? E.g., ... macro technique work with that library. 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 O_LARGEFILE needed just to write a large file?

Is the O_LARGEFILE flag needed if all that I want to do is write a large file (O_WRONLY) or append to a large ... O_WRONLY, so I am not sure. 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 - large integer addition with CUDA

I've been developing a cryptographic algorithm on the GPU and currently stuck with an algorithm to perform large integer ... do that on CUDA ? 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 happens to FILE pointer after file is closed?

I wish to know what happens to FILE pointer after the file is closed. Will it be NULL? Basically, I want to ... any other way to go about 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 - Emulating variable bit-shift using only constant shifts?

I'm trying to find a way to perform an indirect shift-left/right operation without actually using the variable shift ... , a 24 cycle stall. 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 - Assignment operator sequencing in C11 expressions

Introduction The C11 standard (ISO/IEC 9899:2011) has introduced a new definition of side effect sequencing within an ... to C11's terminology? 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 - Sending file descriptor over UNIX domain socket, and select()

I'm using a UNIX domain socket to transfer a file descriptor to another process. This works fine, but when I ... socket is ready for writing. 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 exit a child process and return its status from execvp()?

In my simple custom shell I'm reading commands from the standard input and execute them with execvp(). Before ... Is that enough and correct? 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 memset(&mystruct, 0, sizeof mystruct) same as mystruct = { 0 };?

I'm reading about the initialized values by default of an array/struct and have this question: is memset(&mystruct, ... not, what's difference? 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 simulate memory allocation errors

My C application uses 3rd libraries, which do their own memory management. In order to be robust, my ... My environment is Linux/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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c - Does realloc keep the memory alignment of posix_memalign?

Aligned malloc is posix_memalign, that's OK, but what about the aligned realloc? Does realloc retain the alignment ... Assume Linux and x86_64. 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 - trying to use '#include <stdbool.h>' in VS 2010

I'm trying to use the stdbool.h library file in a C program. When I try to compile, however, an error ... a book on learning C programming. 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 assembly - Handling the IDIV instruction

I am currently writing a simple C compiler, that takes a .c file as input and generates assembly code (X86, ... help will 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 is gcc allowed to speculatively load from a struct?

Example Showing the gcc Optimization and User Code that May Fault The function 'foo' in the snippet below will ... out to be 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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c - "Use of a signed integer operand with a binary bitwise operator" - when using unsigned short

In the following C snippet that checks if the first two bits of a 16-bit sequence are set: bool ... unsigned short not unsigned enough? 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 use MPI_Gatherv for collecting strings of diiferent length from different processor including master node?

I am trying to collect different strings of different length from all processors (including the master node) into a ... example in C for 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 - Installing gtk and compiling using gcc under windows?

I have gcc installed in c:/programfiles (also set as a path variable), and i have all the necessary files for ... don't really know where start. 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 fastest way to transpose the bits in an 8x8 block on bits?

I'm not sure the exact term for what I'm trying to do. I have an 8x8 block of bits stored in 8 ... ? This will run on a dsPIC microcontroller 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 - Implementation of strcmp

I tried to implement strcmp: int strCmp(char string1[], char string2[]) { int i = 0, flag = 0; ... anyone help? And please without pointers! 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 - Theory Behind getchar() and putchar() Functions

I'm working through "The C Programming Language" by K&R and example 1.5 has stumped me: #include <stdio.h> /* ... for 'putchar()' to display? 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 - Reading Public/Private Key from Memory with OpenSSL

I am using Public/Private Keys in my project to encrypt/decrypt some data. I am hosting a public key (" ... and not from a file descriptor. 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 - Number of significant digits for a floating point type

The description for type float in C mentions that the number of significant digits is 6. However, float f = ... for a floating point type? 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 - Effcient way to find longest duplicate string for Python (From Programming Pearls)

From Section 15.2 of Programming Pearls The C codes can be viewed here: http://www.cs.bell-labs.com/cm/cs ... For example, less than 10 seconds) 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 - M_PI not available with gcc --std=c11 but with --std=gnu11?

I noticed M_PI is unavailable on c11. By looking at /usr/include/math.h I can see M_PI is defined if: #if ! ... is defined in c99 and gnu11... 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 - dereferencing type-punned pointer will break strict-aliasing rules

I have a unsigned char pointer which contains a structure.Now I want to do the following unsigned char buffer[24]; ... am I doing wrong here? 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 - Creating a DLL in GCC or Cygwin?

I need help to compile a script ("iterator.c") into a DLL. I can't use VS2010 since it does not ... really important. Thank you in advance. 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 - fseek vs rewind?

I have noticed two methods to return to the beginning of a file FILE *fp = fopen("test.bin", "r") ... difference if any between these methods? See Question&Answers more detail:os...

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

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