C program to find the length of a String without using function strlen()

In the following C program we are counting the number of characters in a given String to find out and display its length on console. Upon execution of this program, the user would be asked to enter a string, then the program would count the chars and would display the length of input string as output.

C Program – finding length of a String without using standard library function strlen

/* C Program to find the length of a String without
 *  using any standard library function 
 */
#include <stdio.h>
int main()
{
    /* Here we are taking a char array of size 
     * 100 which means this array can hold a string 
     * of 100 chars. You can change this as per requirement
     */
    char str[100],i;
    printf("Enter a string: \n");
    scanf("%s",str);

    // '\0' represents end of String
    for(i=0; str[i]!='\0'; ++i);
       printf("\nLength of input string: %d",i);
    
    return 0;
}

Output: