Reverse a string using functions

Method.

1. Read the string (using fgets so that spaces are accepted).
2. countChars() returns the number of characters by counting until the null character '\0'.
3. reverse() copies the characters from the last to the first into a second array and puts '\0' at the end.
4. main() displays the length and the reversed string.

#include <stdio.h>

int countChars(char s[])
{
    int n = 0;
    while (s[n] != '\0')
        n++;
    return n;
}

void reverse(char s[], char r[])
{
    int n = countChars(s);
    for (int i = 0; i < n; i++)
        r[i] = s[n - 1 - i];
    r[n] = '\0';
}

int main(void)
{
    char str[100], rev[100];
    printf("Enter a string: ");
    fgets(str, sizeof str, stdin);
    for (int i = 0; str[i]; i++)            /* remove trailing newline */
        if (str[i] == '\n') str[i] = '\0';
    reverse(str, rev);
    printf("Length = %d\nReverse = %s\n", countChars(str), rev);
    return 0;
}

Sample run

Input: Pulchowk Campus

Enter a string: Length = 15
Reverse = supmaC kwohcluP

The length of "Pulchowk Campus" is 15 (the space is counted).