code:
#include<iostream>
#include<conio.h>
#include<stdio.h>
using namespace std;
void main()
{
char str[100];
int lenth=0;
cout<<"enter string : ";
cin.get(str,100);
for(int i=0;str[i]!='\0';i++)
{
lenth++;
}
cout<<"the length of string :"<<lenth;
getch();
}
output: