Question

In a main function, use a menu system to exercise the usage of all of these functions. The
menu should be in a continuous loop to allow the user to test all functions.

1. Write a recursive function for the following function that does not use recursion.
So, we want to implement the same function using recursion.
void what(int x)
{
while (x > 0)
{
cout<<”say what\n”;
x--;
} //x > 0
}//what

2. Write a recursive function that accepts two arguments, a1 and a2. The function
should return the value of a1 times a2. You should use the knowledge that
multiplication cane be performed by a set of additions. For example,
5 * 3 = 3 + 3 + 3 + 3 + 3

3. Write a recursive function that finds the number of occurrences of a specified
letter in a string. The function accepts a string and a character to look for. For
example, if we call the function countMe(“hello”, ‘l’); the function will return 2.
Ask the user for a string and a character to look for and display the number of
occurrences of the character. If we call the function countMe(“hello”, ‘z’); the
function will return 0.

4. Write a recursive function that returns the value of the following sum:
Sum = 1 + 1/2 + 1/3 + … + 1/n

The program should ask the user for an integer (n) and display the sum So, if n is
entered as 3, the returned value will be 1.8333 = (1+1/2+1/3) . If n is entered as 5,
the returned value be 1+1/2+1/3+1/4+1/5 = 2.2833

Answer 1

Program 1

#include <iostream>
using namespace std;
void what(int);
int main()
{
int x;
cout<<"Enter a number:";
cin>>x;
what(x);

return 0;
}
void what(int x)
{
if(x>0){
cout<<"say what\n";
what(x-1);
}
}

Screenshot of the program 1:

Program 2:

#include <iostream>
using namespace std;
int accepts_two(int,int);
int main()
{
int x,y,result;
cout<<"Enter two numbers:"<<endl;
cin>>x;
cin>>y;
result=accepts_two(x,y);
cout<<"Result="<<result;
return 0;
}
int accepts_two(int x,int y)
{
int static r=0;
if(x>0){
r=r+y;
accepts_two(x-1,y);
  
}
return r;
}

Screenshot of the program 2:

Program 3 :

#include <iostream>
using namespace std;
int countMe(char *,char);
int main()
{
int result;
result=countMe("hello", 'l');
cout<<"Result="<<result;
return 0;
}
int countMe(char *s,char x)
{
int static count=0,r=0;
if(s[r]!='\0'){
if(s[r]==x)
count++;
r++;
countMe(s+1,x);
}
return count;
}

Screenshot of the program 3:

Program 4:

#include <iostream>
using namespace std;
double sum(double);
int main()
{
double result;
int n;
cout<<"Enter n value:";
cin>>n;
result=sum(n);
cout<<"Result="<<result;
return 0;
}
double sum(double n)
{
double static s=0;
if(n>0){
s=s+(1/n);
sum(n-1);
}
return s;
}

Screenshot of the program 4: