Recent questions tagged C

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c - How to work on a sub-matrix in a matrix by pointer?

I have a matrix of size n. Take an example: My recursive function does the processing on the elements that lie in ... to access it with [][]. 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 - using printf to print out floating values

#include<stdio.h> #include<stdlib.h> int main(void) { int x, *ptr_x; float f , *ptr_f; ptr_f = &f; ptr_x ... printed properly even if i use %f ? 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 do I require multiple EOF (CTRL+Z) characters?

As a little background, I am quite new to the C Programming Language and as such have been attempting to work ... the current count and exit? 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 - Arrays decaying into pointers

Please help me understand the programs below. #include<stdio.h> int main() { int a[7]; a[0] = 1976; ... sizeof and & becomes false 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 - Best practice for compute the function return value

Often I built functions, in C, that checks some parameters and return an error code. Which is the best approach ... Which is the best approach? 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 two-dimensional array via pointer

How do I pass the m matrix to foo()? if I am not allowed to change the code or the prototype of foo()? void foo(float ... i+j; foo(???m???); } 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 the order of execution of fork() be determined?

I'm working on an exercise on the textbook "Operating System Concepts 7th Edition", and I'm a bit confused about ... , how could I do that? 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 - Const correctness for array pointers?

Someone made an argument saying that in modern C, we should always pass arrays to functions through an array ... high integrity C++ standard. 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: return type defaults to ‘int’ [-Wreturn-type]

I'm a Linux user who started learning C and I'm trying to compile this source that I typed: #include < ... want to understand what this means 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 scanf() need & operator (address-of) in some cases, and not others?

Why do we need to put a & operator in scanf() for storing values in an integer array but not while storing ... But whats the case with strings? 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 does a for loop without curly braces do?

Hi so basically my question is what does a for loop without any curly braces around it do? So from what I ... Or am I missing something 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 - fgetc, checking EOF

In the book Linux System Programming I have read some like this: fgetc returns the character read as an unsigned char ... where it is not true? 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 - Disable variable-length automatic arrays in gcc

I couldn't disable it even though by using -std=c89 flag. How can I disable 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 - What's the difference between logical SSE intrinsics?

Is there any difference between logical SSE intrinsics for different types? For example if we take OR operation, there ... do the same thing? 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 a Linux executable "compatible" with OS X?

If you compile a program in say, C, on a Linux based platform, then port it to use the MacOS libraries, will it ... , but I'm not really 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 - C11 GCC threads.h not found?

The following code #include <threads.h> Gives me this error: fatal error: threads.h: No such file or ... packages from the Ubuntu repo. 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 C99 features are available in the MS Visual Studio compiler?

It's well known that Microsoft's Visual Studio compiler does not support C99, and it looks like they have no ... list like this one for 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 - When an int is cast to a short and truncated, how is the new value determined?

Can someone clarify what happens when an integer is cast to a short in C? I'm using Raspberry Pi, so I'm ... truncated from 32 bits to 16 bits? 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 - argv[argc] ==?

My professor and a couple of students are arguing about whether argv is null terminated or not. My friend ... someone solve this discussion? 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 does a mutex lock and unlock functions prevents CPU reordering?

As far as I know, a function call acts as a compiler barrier, but not as a CPU barrier. This ... question is about the x86 architecture. 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 can't the size of a static array be made variable?

Related but not quite duplicate as it discusses C++: can we give size of static array a variable I am ... still dependent on a variable siz. 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 - Are file descriptors shared when fork()ing?

Let's say I open a file with open(). Then I fork() my program. Will father and child now share the ... offsets be independent after the fork()? 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 - Need help using qsort with an array of structs

Now, I have seen various examples, but I don't get what they mean. Here's my structure typedef struct profile{ ... with the exact thing I need. 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 a good idea to use C99 VLA compared to malloc/free?

Is it a good idea to use C99 VLA? When is it appropriate to use VLA compared to malloc/free? (since VLA may blow up stack?) 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 multiply an array of int64_t?

I want to vectorize the multiplication of two memory aligned arrays. I didn't find any way to multiply 64*64 ... right data type is __int64_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 - Print int from signal handler using write or async-safe functions

I want to print a number into log or to a terminal using write (or any async-safe function) inside a signal ... , "child terminated", 16); 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 get the length of a function in bytes?

I want to know the length of C function (written by me) at runtime. Any method to get it? It seems sizeof doesn't work 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 - What is the fastest way to convert float to int on x86

What is the fastest way you know to convert a floating-point number to an int on an x86 CPU. Preferrably in C ... just let the compiler do 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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