Recent questions tagged C

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c - Is there any reason not to use fixed width integer types (e.g. uint8_t)?

Assuming you're using a compiler that supports C99 (or even just stdint.h), is there any reason not to use ... how many bytes they are using? 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 - Maximum PID in Linux

I am porting an application from Tru64 to Linux and it uses PID_MAX defined in limits.h. Linux doesn't have that ... hand? Is there a 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 - Merging two sorted linked lists

This is one of the programming questions asked during written test from Microsoft. I am giving the question and ... errors and logic. 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 - Keeping a global reference to the JNIEnv environment

I am storing off JNIEnv in a global so I can call static java methods later. But is it nessasary to store ... ) { //use globalEnvPointer 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 - Fastest way to calculate a 128-bit integer modulo a 64-bit integer

I have a 128-bit unsigned integer A and a 64-bit unsigned integer B. What's the fastest way to calculate A ... your answer differ in this case? 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 are trade offs for "busy wait" vs "sleep"?

This is an extension to my previous question How does blocking mode in unix/linux sockets works? What I ... clear these conflicting thoughts. 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 do I reimplement (or wrap) a syscall function on Linux?

Suppose I want to completely take over the open() system call, maybe to wrap the actual syscall and perform some ... to achieve the same goal. 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 - Debugging child process after fork (follow-fork-mode child configured)

I'm developing an application which the parent forks a child to handle certain tasks. I'm having an ... successfully debug the child process? 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 - Paint Pixels to Screen via Linux FrameBuffer

I was recently struck by a curious idea to take input from /dev/urandom, convert relevant characters to random integers, ... (fbfd); return 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 - Algorithm to generate bit mask

I was facing this unique problem of generating a bit-mask based on the input parameter. For example, if param = 2 ... is a better algorithm ~~~ 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 cast an integer to void pointer?

While working with Threads in C, I'm facing the warning "warning: cast to pointer from integer of different size" ... void * ) as a parameter? 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 bind raw socket to specific interface

My application is running on CentOS 5.5. I'm using raw socket to send data: sd = socket(AF_INET, ... specific network interface (say eth1)? 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 use of typedef?

What is the use of typedef keyword in C ? When is it needed? 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 GCC not complain about undefined references?

Under what situation is it possible for GCC to not throw an "undefined reference" link error message when trying ... exact single line of code. 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 exit() function

I want to know how and when can I use the exit() function like the program in my book: #include<stdio.h> void ... (i.e. close the window)? 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 - Finding the intersecting node from two intersecting linked lists

Suppose there are two singly linked lists both of which intersect at some point and become a single linked ... finding the intersecting node? 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 - Linux Shellcode "Hello, World!"

I have the following working NASM code: global _start section .text _start: mov eax, 0x4 mov ebx, 0x1 mov ecx ... exits fine. 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 - Why does this memory address %fs:0x28 ( fs[0x28] ) have a random value?

I've written a piece of C code and I've disassembled it as well as read the registers to understand how the ... %fs:0x28,%rax is really doing? 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 - Dropping root privileges

I have a daemon which gets started as root (so it can bind to low ports). After initialisation I'd ... back to root privileges afterwards. 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 set up a cron job to run an executable every hour?

I need to set up a cron job that runs an executable compiled using gcc once every hour. I logged in as root ... a way I can solve this problem? 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 - Redefining NULL

I'm writing C code for a system where address 0x0000 is valid and contains port I/O. Therefore, any ... macro when doing static initialization. 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 - Pointer expressions: **ptr++, *++*ptr and ++**ptr use

I am trying my hands on a C pointer literature. In one of the illustrations, I encountered the ... clarification would be 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 - What are scanf("%*s") and scanf("%*d") format identifiers?

What is the practical use of the formats "%*" in scanf(). If this format exists, there has to be ... interger: 12345 372 manav@workstation:~$ 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 - Order of execution for an if with multiple conditionals

In an if statement with multiple conditionals, is the second conditional executed if the outcome of the first is ... use nested if statements? 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 exactly does `-rdynamic` do and when exactly is it needed?

What exactly does -rdynamic (or --export-dynamic at the linker level) do and how does it relate to symbol ... course), which is quite puzzling. 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 to use pthread_exit() and when to use pthread_join() in Linux?

I am new to pthreads, and I am trying to understand it. I saw some examples like the following. I could see that ... // free // close, fclose } 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 - Which is better way to calculate nCr

Approach 1: C(n,r) = n!/(n-r)!r! Approach 2: In the book Combinatorial Algorithms by wilf, i have found ... better way to calculate C(n,r)?. 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 the printf and vprintf function families, and when should I use one over the other?

I understand that the difference between the printf, fprintf, sprintf etc functions and the vprintf, vfprintf, ... to pick vprintf instead? See Question&Answers more detail:os...

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

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