Problem with palindrome sequence for c++ programming

Question

Write a program to check whether a string is palindrome or not.

This program should use recursion!!! AND THIS SHOULD BE IN C++ PROGRAMMING BEGINS WITH #include<iostream> and then using namespace std; !!!!!!!!!!!!!!

Answer 1

using namespace std;

// You can put the namespace call before the #include <iostream>.... it doesn't matter!!!

#include <iostream>

#include <string>

#include <string.h>

//Not sure what types of strings you wanted, so here is

// the recursive routine using C-strings that are NULL termianted

bool IsPalindrome ( char * str)

{

int n;

bool boolReturn;

if ((n=strlen(str))>1)

{

if (str[0]==str[n-1])

{

str[n-1]=0;

boolReturn = true && IsPalindrome(str+1);

}

else

{

boolReturn=false;

}

}

else // one character string is it's own palindrome by default

{

boolReturn=true;

}

return(boolReturn);

}

/***************************************************

Here is Andrew's function ...

I rewrote it a little bit so that it has only

one return statement;

---------------------------------------------------------

Functions are OVERLOADED: same function names

and return types, but one takes a C-String

and the other std::string

*******************************************************/

bool IsPalindrome(string s)

{

bool boolReturn;

if (s.length() <= 1)

{

boolReturn = true;

}

else

if (s[0] == s[s.length()-1])

{

boolReturn = true && IsPalindrome(s.substr(1,s.length()-2));

}

else

{

boolReturn=false;

}

return(boolReturn);

}

//Here is the main function that YOU were supposed to write

int main()

{

char str[255];

strcpy(str,"ABBA");

cout << IsPalindrome(str)<<endl; //1

strcpy(str,(char*)"HANNAH");

cout << IsPalindrome(str)<<endl; //1

strcpy(str,(char*)"RADAR");

cout << IsPalindrome(str)<<endl; //1

strcpy(str,(char*)"RAZOR");

cout << IsPalindrome(str)<<endl; //0

strcpy(str,(char*)"ABCDEFGHIJKLMNOPQRSTUVWXYZYXWVUTSRQPONMLKJIHGFEDCBA");

cout << IsPalindrome(str) << endl; //1

strcpy(str,(char*)"ABCDEFGHIJKLMNOPQRSTUVWXYZYZWVUTSRQPOMNLKJIHGFEDCBA");

cout << IsPalindrome(str) << endl; //0 the M and N are out of order

cout << "***********************************************" << endl;

//same output

string Str = "ABBA";

cout << IsPalindrome(Str)<< endl;

Str = "HANNAH";

cout << IsPalindrome(Str)<< endl;

Str = "RADAR";

cout << IsPalindrome(Str)<< endl;

Str = "RAZOR";

cout << IsPalindrome(Str)<< endl;

Str="ABCDEFGHIJKLMNOPQRSTUVWXYZYXWVUTSRQPONMLKJIHGFEDCBA" ;

cout << IsPalindrome(Str)<< endl;

Str = "ABCDEFGHIJKLMNOPQRSTUVWXYZYZWVUTSRQPOMNLKJIHGFEDCBA";

cout << IsPalindrome(Str)<< endl;

}

Answer 2

bool ispalindrome(string s) {

if (s.length() <= 1) {

return true;

}

if (s[0] == s[s.length()-1]) {

return ispalindrome(s.substr(1,s.length()-2));

} else {

return false;

}

}