Recent questions tagged C

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I've already got some code to read a text file using fscanf(), and now I need it modified so that fields ... why I simplified it to fscanf(). 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 - Reading from a file and storing in array

I've written the following program to read line by line from a file and store it in the words ... acknowledgement impossibility never gave up 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 - semaphore implementation

I am getting error in the following program. I want to demonstrate how two processes can share a variable using ... (&semid); 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 - What is the maximum size of static array that can be declared in GCC?

How its determined ? Does this depend on the compiler/Architecture/Host system ? Example: int array[0x8000000000000000]; ... ' is too large". 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 - Update shared libraries without restarting processes

If my process is loading a .so library and if a new version of the library is available is it possible to ... is to just reload the processes. 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 /dev/input

I have an USB RFID card reader which emulates keyboard. So when i put an card to it i see the string on a terminal ... } close(fd); 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 - Linux: Bind UDP listening socket to specific interface (or find out the interface a datagram came in from)?

I have a daemon I'm working on that listens for UDP broadcast packets and responds also by UDP. When a ... applies only to out-going packets. 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 convert a 64bit integer to a char array and back?

I am having trouble converting a int64_t to a char array and back. I don't know what is wrong with the code ... shift count >= width of type 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 does sched_setaffinity() work?

I am trying to understand how the linux syscall sched_setaffinity() works. This is a follow-on from my question ... to accomplish this task.) 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 - Duplicate image detection algorithms?

I am thinking about creating a database system for images where they are stored with compact signatures and then ... about such an algorithm. 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 - Which variable types/sizes are atomic on STM32 microcontrollers?

Here are the data types on STM32 microcontrollers: http://www.keil.com/support/man/docs/armcc/armcc_chr1359125009502.htm. ... -in-arm-cortex-m/ 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 - Fast 24-bit array -> 32-bit array conversion?

Quick Summary: I have an array of 24-bit values. Any suggestion on how to quickly expand the individual 24- ... be missing something obvious... 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 - Casting an int pointer to a char ptr and vice versa

The problem is simple. As I understand, GCC maintains that chars will be byte-aligned and ints 4-byte-aligned in a ... cptr2 = (char *) iptr2; 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 - Max identifier length

Where can I find what is the maximum identifier length in C? In which header file is that limit specified? 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 - Pointer to Array of Pointers

I have an array of int pointers int* arr[MAX]; and I want to store its address in another variable. How do I ... int (what here?) val = &arr; 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 - is SIGSEGV delivered to each thread?

I have a program in Linux which is multithreaded. There are certain memory areas in which I'm interested to ... to execute the signal handler? 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 - Minimal implementation of sprintf or printf

I'm working on an embedded DSP where speed is crucial, and memory is very short. At the moment, sprintf uses ... be more suitable for my usage? 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 - Whats wrong with array declaration: "invalid digit in octal constant"?

int arr[20][20] = { {08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08}, {49,49, ... 24:46: error: invalid digit "8" in octal constant 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 - End of File in stdin

A question about this has been asked here End of File (EOF) in C but it still doesn't completely solve my ... file? is this it? Thank you 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 subtract two unsigned ints with wrap around or overflow

There are two unsigned ints (x and y) that need to be subtracted. x is always larger than y. However, ... statement (target language is C)? 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 - Best machine-optimized polynomial minimax approximation to arctangent on [-1,1]?

For the simple and efficient implementation of fast math functions with reasonable accuracy, polynomial minimax approximations ... return r; } See Question&Answers more detail:os...

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

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453 views

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c - Is a dereferenced pointer a valid lvalue?

Assuming the definition: int i = 10; int *p = &i; Why is *p a valid lvalue here: *p+=10; Shouldn't ... hence generate a "Not an lvalue" error? 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 - multiple definition of inline function

I have gone through some posts related to this topic but was not able to sort out my doubt completely. This ... only understand the output 6. 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 - getopt_long() -- proper way to use it?

OK, I have searched and found the following two StackOverflow topics that started me in the right direction: ... via command line first. 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 - Overflow appears even when using unsigned long int

When I make the following calculation: unsigned long long int data_size = 60123456 * 128 * sizeof(double); ... someone explain why? Thank you 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 can I get Eclipse to index code inside #ifdef .... #endif

I'm using eclipse to work on some c code and it is not indexing code inside conditional compilation blocks ... to index the feature_a function? See Question&Answers more detail:os...

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

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636 views

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c - printf with sizeof on 32 vs 64 platforms: how do I handle format code in platform independent manner?

I have some code that prints the amount of memory used by the program. The line is similar to this: printf("The ... way that I'm not realizing. 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 - What kind of data type is "long long"?

I don't know this type. Is that the biggest one from all? I think it is an integer type, right? Or ... floating point thing? Bigger than double? See Question&Answers more detail:os...

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

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