01 #include <stdio.h>
02 
03 int main()
04 {
05     char str[20];
06     int i=0;
07     int len=0;
08 
09     printf("Enter any string - ");
10     gets(str);
11 
12     while(str[i]!='')
13     {
14         i++;
15         len++;
16     }
17 
18     printf("Length of the string is - %d n",len);
19 
20     return 0;
21 }

OUTPUT :

Enter any string - Hello World
Length of the string is - 11