How do I replace a space with a new line?

Question

How do I replace a space with a newline ("\n") in a string using C?

Answer 1

Your question is quite vague.

Here is a simplistic filter to change all spaces in the input stream into newlines:

#include <stdio.h>

int main(void) {
    int c;

    while ((c = getchar()) != EOF) {
        putchar(c == ' ' ? '\n' : c);
    }
    return 0;
}

EDIT:

If you are interested in modifying a string, you should be aware that string literals are not modifiable, attempting to modify them has undefined behavior.

You should locate the space characters and store newline characters ('\n') at the corresponding offsets.

You can use a pointer and the strchr() function:

char *p = strchr(string, ' ');
if (p != NULL) {
    *p = '\n';
}

Handling all spaces in a loop:

for (char *p = string; (p = strchr(p, ' ')) != NULL; p++) {
    *p = '\n';
}

Or you can use a for loop with an index variable:

for (size_t i = 0; string[i] != '\0'; i++) {
    if (string[i] == ' ') {
        string[i] = '\n';
        //break;   // uncomment the break if you want a single space changed
    }
}