text: // calculate length of string without using predefined message
  
  #include<stdio.h>
  #include<conio.h>
  
  int main()
  {
  	char s[20];
  	int i;
  	
  	printf("Enter a string: ");
  	gets(s);     // s -> &s[0]
  	
  	for(i=0; s[i] != '\0'; i++);
  	
  	printf("Length is %d", i);
  	
  	getch();
  }
  