Question

c++

Write a function that uses recursion to raise a number to a power. The function should accept two arguments: the number to be raised and the exponent. Assume that the exponent is a nonnegative integer. Demonstrate the function in a program.

Write a function that accepts an integer argument and returns the sum of all the integers from 1 up to the number passed as an argument. For example, if 50 is passed as an argument, the function will return the sum of 1,2,3,...,50. Use recursion to calculate the sum. Demonstrate the function in a program.

Write a recursive function that accepts a string object as its argument and prints the string in reverse order. Demonstrate the function in a driver program.

Answer 1

Program 1:

#include<iostream>

using namespace std;

//function prototype

int power(int, int);

int main()

{

int n, exp;

//prompt and read a number

cout << "Enter a number: ";

cin >> n;

//prompt and read the exponent

cout << "Enter the exponent: ";

cin >> exp;

//display result

cout << "The value after raising " << n <<" to exponent " << exp <<" is: " << power(n,exp);

return 0;

}

//function that returns the value of the number raised to an exponent

int power(int n, int exponent)

{

//if exponent is not 0

if (exponent != 0)

//call the function recursively by passing n and exponent-1 as parameters multiply the result to n

return (n*power(n, exponent-1));

//if exponent is 0 return 1

else

return 1;

}

Output:

D:Madhuri CAndCpp'Raise ToPower.exe Enter a number 4 Enter the exponent 4 The value after raising 4 to exponent 4 is:256 Process exited after 2.205 seconds with return value 0 Press any key to continue - . -

Program 2:

#include<iostream>

using namespace std;

//function prototype

int sum(int);

int main()

{

int n;

//prompt and read a number

cout << "Enter a number: ";

cin >> n;

//display result

cout << "The sum of numbers from 1 to " << n << " is: " << sum(n);

return 0;

}

//function that takes a n as parameter and returns the sum of numbers from 1 to n

int sum(int n)

{

//if n is not 0

if (n != 0)

//call the function recursively by passing n-1 as parameters adding the result to n

return (n + sum(n-1));

//if n is 0 return n

else

return n;

}

Output:

D:Madhuri CAndCpp'RecursiveSum.exe Enter a number: 50 he sum of numbers from 1 Process exited after 2.151 seconds with return value 0 Press any key to continue . - - to 58 is: 1275

Program 3:

#include<iostream>

using namespace std;

//function prototype

void reverse(string);

int main()

{

string str;

//prompt and read a string

cout << "Enter a string: ";

getline(cin, str);

//print reverse of string using reverse method

reverse(str);

return 0;   

}

//function that takes a string as parameter and prints its reverse

void reverse(string str)

{

//get the length of the string

int strLength = str.size();

//if length is 1 print the string

if(strLength != 1)

{

//print the last character in the string

cout << str[strLength - 1];

//call the function recursively by removing the last character in the string

reverse(str.substr(0, strLength - 1));

}

else

cout << str << endl;

}

Output: