Write a recursive, int-valued function, len, that accepts a string and returns the number of characters in the string. the length of a string is: 0 if the string is the empty string (""). 1 more than the length of the rest of the string beyond the first character.

The program to this question can be given as:

Program:

#include<iostream> //include header file.

using namespace std; //using namespace

int len(string s) //define method.

{

if(s=="") //if block

{

return 0; //return value.

}

else //else block

{

return 1+len(s.erase(0,1)) ; //return value.

}

}

int main() //main method.

{

   string s; //define variable.

   int X1; //define variable.

   cout<<"Enter string value: "; //message.

   cin>>s; //input string value.

   X1=len(s); //calling function that holds value in x1 variable

   cout<<X1; //print variable x value.

   return 0;

}

Output:

Enter string value: xxth

4

Explanation:

The description of the above C++ language program can be given as:

answerparameter;