Recent questions tagged C

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c - Variadic function (va_arg) doesn't work with float?

I have a variadic function which takes a float parameter. Why doesn't it work? va_arg(arg, float) 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 - Inline assembly that clobbers the red zone

I'm writing a cryptography program, and the core (a wide multiply routine) is written in x86-64 assembly, both ... it won't put anything there. 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 - Print out value of stack pointer

How can I print out the current value at the stack pointer in C in Linux (Debian and Ubuntu)? I tried google but found no results. 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 - log2 not found in my math.h?

I'm using a fairly new install of Visual C++ 2008 Express. I'm trying to compile a program that uses the ... that directory... Where is log2? 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 make main thread wait for all child threads finish?

I intend to fire 2 threads in the main thread, and the main thread should wait till all the 2 child threads ... the job, but any other way? 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 - looping through enum values

Is it possible to loop through enum values in Objective-C? 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 - undefined reference 'shm_open', already add -lrt flag here

I just have a system crash and reinstall Ubuntu 11.10, and my code produces this strange error. I wrote a ... why does it still not compile? 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 - Loading PE Headers

Basically, what I am trying to do is to find last section of PE file. I have read PE specification very ... Any ideas ? Thanks 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 - Passing a multidimensional array of variable size

I'm trying to understand what "best practice" (or really any practice) is for passing a multidimensional array to a ... (arry2, a2, b2); } 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 S_ISREG() and S_ISDIR() POSIX Macros?

This is a C program I wrote to recursively navigate and output directories and regular files. It compiles and runs fine ... , depth, argv); } } 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 - Building a shared library using gcc on Linux and MinGW on Windows

I'm having trouble with generating a build setup that allows shared libraries to be built in both Linux and Windows using ... 4.7.2 on Windows. 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 - Reliably determine the number of elements in an array

Every C programmer can determine the number of elements in an array with this well-known macro: #define NUM_ELEMS(a) ( ... for me in heaven? :) 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 purpose of a these #define within an enum?

I found this code in the linux headers, /usr/include/dirent.h: enum { DT_UNKNOWN = 0, # define DT_UNKNOWN ... then compile to the int 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 - *nix select and exceptfds/errorfds semantics

The select syscall takes 3 filedescriptor sets for watching fds for readable/writeable and "exceptions" on ... kinds of descriptors? 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 correct printf specifier for printing pid_t

I'm currently using a explicit cast to long and using %ld for printing pid_t, is there a specifier such as ... the best way of printing pid_t? See Question&Answers more detail:os...

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

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756 views

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c - How to write/read to FLASH on STM32F4, Cortex M4

I want to write a variable, for example an integer with the number 5 to the FLASH and then after the power ... manual, page 71: STM32 Manual See Question&Answers more detail:os...

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

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615 views

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c - read file backwards (last line first)

file looks like this: abcd efgh ijkl I want to read the file using C so that it read the last line ... the reverse order? Is that possible? 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 - defining a 2D array with malloc and modifying it

How do i define a 2D array using malloc ? (lets say 10X20). second, can i increase number of rows or cols ... will be 10x30 or 15x20? thank! See Question&Answers more detail:os...

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

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630 views

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c - forcing a program to flush its standard output when redirected

i have a closed source program that prints output to standard output. i need to parse the output. so i redirect ... the output to get flushed? 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 it possible to have pipe between two child processes created by same parent (LINUX, POSIX)

I have multiple child "forked" by the same parent and I try to construct pipe connection between all these child ... that arises. 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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528 views

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c - GCC 4.7 Source Character Encoding and Execution Character Encoding For String Literals?

Does GCC 4.7 on Linux/x86_64 have a default character encoding by which it validates and decodes the ... transcode between character encodings?) 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 local and register variables be declared extern?

I have been wondering whether an extern can be declared locally and a register variable. If it can be what would be the restrictions imposed? See Question&Answers more detail:os...

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

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892 views

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c - In clang, how do you use per-function optimization attributes?

I'm trying to compile a specific function with no optimization using clang, in order to prevent certain ... nothing changed the 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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480 views

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c - Decimal to Binary

I have a number that I would like to convert to binary (from decimal) in C. I would like my binary to always ... to be represented in a 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 - When does underflow occur?

I get into a situation where calculating 1.77e-308/10 triggers an underflow exception, but calculating 1.777e-308 ... above via this online IDE. See Question&Answers more detail:os...

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

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774 views

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c - Pass va_list or pointer to va_list?

Suppose I have a function which takes variadic arguments (...) or a va_list passed from another such ... some particular implementation allows. See Question&Answers more detail:os...

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

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410 views

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c - Does GCC's __attribute__((__packed__)) retain the original ordering?

Purpose I am writing a network program in C (specifically gnu89) and I would like to simplify things by reinterpreting ... (int) on the client). See Question&Answers more detail:os...

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

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308 views

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c - log(10.0) can compile but log(0.0) cannot with undefined reference?

For the following C source code: #include <math.h> int main(void) { double x; x = log(0.0); ... question is about a missing linking 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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