string length in c without using strlen and string header

1#include <stdio.h>
2// function for string length
3int string_length(char str[])
4{
5    int i;
6    // you can use while loop
7    for( i = 0; str[i] != '\0';i++);
8    return i;
9}
10int main()
11{
12    // declaring character array
13    char your_name[20]; // you can change the maximum size of string
14    printf("Type you full Name : ");
15    // taking input from user
16    gets(your_name);
17    // using string length function
18    int length = string_length(your_name);
19    // printing string length
20    printf("\nLength of your name (%s) is : %d \n\n",your_name,length);
21
22}
23