[HELP] My capitalization program is not working

The problem in my simple learning program is the, basically, it doesn't work and it prints out Segmentation fault (core dumped). I just want to know why it does that and what are the possible solutions.

EDIT: That's not really the main problem. Even if I just assign a value to input, it still prints out the error.

Code:

#include <stdio.h>#include <string.h>


char *cap(char *);


int main(int argc, char *argv[]) {
	char *input = "Hello World!";


	printf("CAPITALIZED: ");
	cap(input);


	return 0;
}


char *cap(char *input) {
	int i, n;


	for(i = 0, n = strlen(input); i < n; i++) {
		if(input[i] >= 'a' && input[i] <= 'z') {
			input[i] -= ('a' - 'A');
			printf("%c", input[i]);
		}
		printf("\n");
	}
}

You're giving scanf the address of your pointer, and when the user inputs data, the stack will get overwritten until the input runs out and/or the program crashes.

Also, you need to allocate memory for "input", because right now it doesn't point to any valid memory location.

I haven't tested it, but what size have the 'input' buffer? If is 0 bytes you shouldn't have to scanf anything into it no?

Niara

Ups sorry memcpy, I haven't seen your post

That's not really the problem. I just wanted users to give me an input. But even if I substitute it with a constant value, the core still gets dumped...

How are you substituting it with a "constant value"? Post the code.

Also, you should check out <ctype.h>, using the functions provided in this header will simplify your code, especially toupper().

Originally Posted by memcpy

How are you substituting it with a "constant value"? Post the code.

Also, you should check out <ctype.h>, using the functions provided in this header will simplify your code, especially toupper().

I know those things but I want to learn how this things work and be able to recreate it with on my own way. The code is already updated in the 1st post

Stop guessing and read about strings

In your current code you are trying to modify a constant string.
Instead of this:

char *input = "Hello World!";

try this

char input[] = "Hello World!";