Recent questions tagged C

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c - How to only accept a certain precision (so many decimals places) in scanf?

In scanf() function I want to take only upto decimal values.Can we achieve it? For example for displaying upto ... do it for scanf() function. 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 - pow() cast to integer, unexpected result

I have some problems using an integer cast for the pow() function in the C programming language. The compiler I ... error from me, compiler bug? 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 x += 1 more efficient than x = x + 1?

In x = x + 1, is x evaluated twice? If so, does that mean in x += 1, x is only evaluated once? How ... array. Any ideas why this is the 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 - Performance: memset

I have simple C code that does this (pseudo code): #define N 100000000 int *DataSrc = (int *) malloc(N); int * ... if I don't call memset()? 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 able to get flock at the same time

I was under the impression that flock(2) is thread safe, I recently, ran across the case in the code, where ... some error 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 - Is it possible to distinguish the error returned by fgets

Upon looking at the ISO C11 standard for fgets §7.21.7.2, 3, the return value is stated regarding the ... the two cases caused the error? 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 I use sizeof in a preprocessor condition?

I understand that sizeof is an operator, which is evaluated at compile time to an integer constant. But it seem ... is such usage not allowed? 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 floating point calculations be made deterministic?

Floating point calculation is neither associative nor distributive on processors. So, (a + b) + c is ... calculations in multithreaded programs? 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 the "true" result of >, <, !, &&, || or == defined?

When I for instance write 7>1 in C (say C99 if this is not an always-been feature), can I expect the ... Does this hold for all bool operators? 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: Why is sig_atomic_t typedef'ed to int?

On my Linux box, sig_atomic_t is a plain old int. Do ints posses a special atomic quality? ... ; typedef __sig_atomic_t sig_atomic_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 - I need a mix of strtok and strtok_single

I have the following string that I am trying to parse for variables. char data[]="[email protected]&cc ... can handle consecutive delimiters? 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 prevent input using scanf from overflowing?

I'm relatively new to C and would like to know how to prevent an overflow from input... So for example, I ... I go about restricting the input? 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 have to input EOF 3 times when using fgets?

So basically I want to copy everything i write to stdin (including newline char) to string for hash purposes. ... anything you need. Thank you. 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 - fclose() causing segmentation fault

I have a tab-delimited text file that I am parsing. Its first column contains strings of the format chrX, ... a Segmentation Fault to occur? 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 - strcat() implementation works but causes a core dump at the end

My implementation of strcat(char*, const char*) seems to work but then it causes a core dump. strcat() implementation ... ) What did I do wrong? 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 the exec() family of functions doesn't execute the code after exec()?

the man page says that "The exec() family of functions replaces the current process image with a new process image. ... ; perror("exec failed"); 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 is 0 moved to stack when using return value?

I'm experimenting disassembling clang binaries of simple C programs (compiled with -O0), and I'm confused about a ... what is it's purpose? 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 - getchar() != EOF

I am running the following program from the C Programming Language book: #include <stdio.h> main() { int c; ... am running on a UNIX system. 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 is scanf("%hhu", char*) overwriting other variables when they are local?

The title says it all. I'm using GCC 4.7.1 (bundled with CodeBlocks) and I faced a strange issue. Consider this: ... 1 0 0 0 255 255 255 255 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 - literal constant vs variable in math library

So, I know that in C you need to link the code to the math library, libm, to be able to use its functions. ... m using gcc 4.4.5 under linux. 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 Parentheses in Define Preprocessor Statements

So I was wondering when is to use #define xxx (yyy) vs #define xxx yyy My project includes a ... ) or #define AD0_COMPARETIME AD0_ADMD_CT 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 - sin, cos, tan and rounding error

I'm doing some trigonometry calculations in C/C++ and am running into problems with rounding errors. For example, ... quite a few ULPs apart. 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 - functions returning char pointer

I came across lot of functions returning char pointers in one legacy application. Some of them returning pointers to local ... array*/ f2(arr); 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 X11 window span multiple monitors

I'm trying to use XResizeWindow() to make a window which will span 2 monitors, but the ?window manager? is ... end 0 total 1200 clock 50.0Hz 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 - Detecting mismatched array <-> enum initializers

When doing embedded programming with C, many times I find myself doing maps with enum and array because they are ... the length of the array? 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 padding are added, if char comes after int?

For example, there is a structure struct A { char a; int i; }; In this case, we have a[1 byte] + padding[3 ... I get 16. How this is 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 - Cast T[][] to T*

Is it safe to cast a 2D array of type T to T* and dereference the elements? Since the memory layout of 2D ... the bounds of the first array. 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 I treat a struct like an array?

I have a struct for holding a 4D vector struct { float x; float y; float z; float w; } ... doSomethingWithVectors( (float *) &myVector)? See Question&Answers more detail:os...

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

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