Recent questions tagged C

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c - How to add multiple header include and library directories to the search path in a single gcc command?

How to add multiple header include and library directories to the search path in a single gcc command? 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's the difference between gets and scanf?

If the code is scanf("%s ",message) vs gets(message) what's the difference?It seems that both of them get input to message. 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 - Switch case weird scoping

Reviewing some 3rd party C code I came across something like: switch (state) { case 0: if (c=='A') { // open ... if break absent in case 0 or 1. 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 - prefetching data at L1 and L2

In Agner Fog's manual Optimizing software in C++ in section 9.10 "Cahce contentions in large data structures" ... is dominating the L1 times. 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 - Difference between dereferencing pointer and accessing array elements

I remember an example where the difference between pointers and arrays was demonstrated. An array decays to a pointer to ... dword ptr [x2],edx 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 effective type of an object written by memset?

Code 1: unsigned int *p = malloc(sizeof *p); memset(p, 0x55, sizeof *p); unsigned int u = *p; Code ... characters of the object pointed to by s. 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 malloc() use brk() or mmap()?

c code: // program break mechanism // TLPI exercise 7-1 #include <stdio.h> #include <stdlib.h> void ... in man page for mallopt(). 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 - printf, wprintf, %s, %S, %ls, char* and wchar*: Errors not announced by a compiler warning?

I have tried the following code: wprintf(L"1 %s ","some string"); //Good wprintf(L"2 %s ",L"some string"); / ... 4 %ls ",L"some string"); //Good 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 API do I call to get the system uptime?

I would like to get the system uptime from within a C application running on a linux-based system. I ... process records obtained from wtmp? 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 there a way to get warned about unused functions?

I'd like to find unused functions in a codebase - including across compilations units. I'm using gcc as my ... to stick with gcc if 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 - How to sort an array of string alphabetically (case sensitive, nonstandard collation)

I need a c language code to sort some strings and it should be case sensitive and for the same letter in upper- and ... %s ", name[i]); } } 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 a function prototype typedef be used in function definitions?

I have a series of functions with the same prototype, say int func1(int a, int b) { // ... } int ... understands that SpFunc is a function 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 - How can I get argv[] as int?

i have a piece of code like this: int main (int argc, char *argv[]) { printf("%d",(int)argv[1]); printf(" ... I get argv[] as a int? many 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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c - Size of pid_t, uid_t, gid_t on Linux

On Linux systems (either 32- or 64-bit), what is the size of pid_t, uid_t, and gid_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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c - Confusion about pointers and multidimensional arrays

If the following is possible: MyFunction(int *array, int size) { for(int i=0 ; i<size ; i++) { printf( %d , ... 8}; MyFunction(array, 3, 3); } 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 (int *)0 a null pointer?

This could be thought of as an extension to this question (I'm interested in C only, but adding C++ to complete ... int *)0 as a null pointer. 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 Other Process' Memory in OS X?

I've been trying to understand how to read the memory of other processes on Mac OS X, but I'm not having ... of another process on Mac OS X? 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 your own syntax highlighting in GEdit?

How do you add a 'keyword' to the GEdit list of keywords? I basiclly want to make the printf function look ... keyword. printf("Hello World "); 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 - Get index of substring

I have char * source, and I want extract from it subsrting, that I know is beginning from symbols "abc", and ... of the substring in pure 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 - How can I call a function using a function pointer?

Suppose I have these three functions: bool A(); bool B(); bool C(); How do I call one of these ... how do I declare the function pointer? 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 does the Win32-API have so many custom types?

I'm new to the Win32 API and the many new types begin to confuse me. Some functions take 1-2 ints and 3 ... have just used char* instead, or? 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 should I pass or return a struct by value?

A struct can be either passed/returned by value or passed/returned by reference (via a pointer) in C. The ... should be passed by reference. 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 - warning: left shift count >= width of type

I'm very new to dealing with bits and have got stuck on the following warning when compiling: 7: ... have I misunderstood something fundamental? 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's the best way to do a reverse 'for' loop with an unsigned index?

My first attempt of reverse for loop that does something n times was something like: for ( unsigned int i = n ... integers. Any ideas? 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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c - Timing CUDA operations

I need to time a CUDA kernel execution. The Best Practices Guide says that we can use either events or ... waaaay too pessimistic (events). 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 can I take a screenshot and save it as JPEG on Windows?

I'm trying to find a (somewhat) easy way to take a screenshot on window and save the resulting HBITMAP as ... (gdiplusToken); return iRes; } 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 - Multiple threads and CPU cache

I am implementing an image filtering operation in C using multiple threads and making it as optimized as ... cache efficiently this 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 - Non-blocking pipe using popen?

I'd like to open a pipe using popen() and have non-blocking 'read' access to it. How can I achieve ... I found were all blocking/synchronous) See Question&Answers more detail:os...

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

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