Recent questions tagged C

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c - Floating point arithmetic and machine epsilon

I'm trying to compute an approximation of the epsilon value for the float type (and I know it's already in the ... a little to make it clearer. 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 - Read from a file that is continuously being updated

I am writing some C code to process some data in a file, but I just learned that the file is going to be ... that. Does anyone have any advice? 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 - Moving to different Linux build system, getting error: undefined symbol: stat

This may just be an issue with the build system I am migrating to, but I'll include differences in the two ... time error on the new system? 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 - Memory Clobbering Error

I have a small piece of code. I compiled it with -lmcheck as I am trying to debug a code where I have the same ... ; } free(ptr); 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 - How to check if a void* pointer can be safely cast to something else?

Let's say I have this function, which is part of some gui toolkit: typedef struct _My_Struct My_Struct; /* struct ... cast back to My_Struct* ? 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 - gcc argument register spilling on x86-64

I'm doing some experimenting with x86-64 assembly. Having compiled this dummy function: long myfunc(long a, long b, ... - why would gcc do that? 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 - Malloc header contents

So in most implementations malloc stores an header before the allocated memory to keep track of the allocated memory ... What is happening 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 - Valgrind Warning: Should I Take It Seriously

Background: I have a small routine that mimics fgets(character, 2, fp) except it takes a character from a ... I worry about this warning? 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 - For loop without the second condition, i.e. the boolean check?

I have to write a function that calculates the floor of log base 16 of an unsigned int passed in. There ... iterate while a condition is met? 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 tell gcc to instrument the code with calls to my own function each _line_ of code?

For example, there is the source: void my_special_debugging_function(const char* function_name, const char* file_name, int ... , not _CPU_ one 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 - Global integer array with No dimension

What is the concept when we define a global array with no dimension This shows output as 16. #include <stdio.h> ... (arr) doesn't work. 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 - Convert ASCII character to x11 keycode

I have a small program that takes input in the form of ascii characters. I need to be able to convert these ... a large switch case work best? 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 - Linux syscalls and errno

Context: I am trying to write a small C program with inline asm that should run under Linux on an x86_64 system and ... World "; long len = 12; 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 - Programs with the scanf not working properly in NetBeans

I've installed NetBeans 7.0.1 today When I try to execute C program with "scanf" in it it's giving strange ... should I do to make this right? 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 - char array not assignable

Okay, so I want to save a word in a char array but it gives me a error Here's my code #include <stdio.h> ... on uC's for a couple of years. 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 would one use mmap map_fixed

I've been looking at the different flags for the mmap function, namely MAP_FIXED, MAP_SHARED, MAP_PRIVATE. Can someone ... in the first place. 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 - Notify/Signal when memory mapped file modified

I am currently sharing data (<1KB) between multiple processes by memory-mapping. 1 "writer" process and multiple " ... after calling msync()). 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 - vectorized strlen getting away with reading unallocated memory

While studying OSX 10.9.4's implementation of strlen, I notice that it always compares a chunk of 16-bytes ... that had the least reputation. See Question&Answers more detail:os...

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

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866 views

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c - Is a misaligned load due to a cast undefined behavior?

Is a misaligned load due a a cast from void* undefined behavior? Here's what I am seeing with Clang and its ... the strict aliasing rule in C99 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 - Create char array of integer using digits as size

I am trying to create a char array in C, to fill it with the digits of an int, but the int can be of any ... know if is a way of achieving 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 - Segmentation fault - char pointer

In the code below, the line: *end = *front; gives a segmentation fault. I asked a similar question here but I'm not ... end--; } } return num; } 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 tracker server NOT understand my request? (Bittorrent protocol)

I'm trying to implement Bittorent in C. First of all, before writing a code snippet, I tried to used a web ... be awesome. Thank you 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 - How do I use a Linux System call from a Linux Kernel Module

I am having some difficulty calling a system call from inside a Linux Kernel Module. The system calls ... ); module_exit(finish_exit); 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 - Actual implementation of EOF different from -1

POSIX defines EOF as a macro expanding to a negative value: The header shall define the following macro which ... where this happens is valid. 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 - Buffer Overflow not working

I was trying to do a buffer overflow (I'm using Linux) on a simple program that requires a password. Here' ... help me? Thanks 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 - Add a Timeout for getchar()

I need to add a timeout function for getchar() in my program. What do I do so that when my program reaches ... so kbhit is not an option. See Question&Answers more detail:os...

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

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988 views

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c - Gcc uses sqrt without including math.h

Anyone knows why this c program compiles and uses the sqrt of math.h? this would output 2.236068 main.c ... currently using mingw GCC on windows 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 compute log with the preprocessor

How do I do log(x) with the preprocessor on windows ? like: #define A log(4)/log(2) and after in my ... with the preprocessor ! not in run 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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