Question

Write a recursive function that takes a string as an input and returns the reverse of the string.

Write a recursive function rec_string that produces the output shown below for the corresponding function calls. Write a main function to test the function.

Method call rec_string(‘abcde’), will produce the following output:

*

e

de

cde

bcde

abcde

Method call rec_string(‘abc’), will produce the following output:

*

c

bc

abc

Answer 1

I have written the program in c++

Question 1:

Here is code:

string rec_string(string str){
if (str.length() == 1) {
return str;
}else{
return reverseStringRecursively(str.substr(1,str.length())) + str.at(0);
}
}

Question 2:

Here is function:

void rec_string(string str){
static int count = 0;
if(count == 0) // if count is 0 prints only *
cout << "*" << endl;
   else
   {
       // loops from str length - count to str end
   for(int i = str.length() - count; i < str.length() ; i++)
   cout << str[i];
cout << endl;
}
if(count == str.length()) // if count read str length then exit
return;
count++;
rec_string(str);
}

Sample main function to test:

#include <iostream>
#include <string>
using namespace std;

void rec_string(string str){
static int count = 0;
if(count == 0) // if count is 0 prints only *
cout << "*" << endl;
   else
   {
       // loops from str length - count to str end
   for(int i = str.length() - count; i < str.length() ; i++)
   cout << str[i];
cout << endl;
}
if(count == str.length()) // if count read str length then exit
return;
count++;
rec_string(str);
}
int main()
{
rec_string("abcde");
return 0;
}

Output:

dle cde bcde abcdle

Answer 2

#include<stdio.h>
void revs(char *p)
{
    if(*p)
    revs(p+1);
    printf("%c",*p);
}
int main()
{
    char name[40];
    scanf("%[^\n]s",name);
    revs(name);
}