Introduction

I have used CodeBlocks compiler for debugging purpose. But you can use any C++ programming language compiler as per your availability.

#include <iostream>
#include <math.h>
using namespace std;
 
//function declaration
int stringLength(char *);
 
int main()
{
    char text[100];
    int length;
 
    cout<<"Enter text (max- 100 characters): ";
    cin>>text;
 
    length = stringLength(text);
 
    cout<<"Input text is: "<<text<<endl;
    cout<<"Length is: "<<length<<endl;
 
    return 0;
}
 
 
int stringLength(char *str)
{
    int len=0;
 
    //calculating string length
    for(len=0; str[len]!='\0'; len++);
 
    //returning len
    return len;
}

Result