Program check the length of string without using string function i c++

#include<stdio.h>

#include<conio.h>

#include<iostream.h>

void main()

{

char str[50];

int i;

clrscr();

cout<<"\n"<<"Enter a String: ";

cin.getline(str,50);

cout<<"\n"<<str<<"\n";

for(i=0;str[i]!='\0';i++);

cout<<i;

getch();

}