/*
C++ Palindrome Checker program by lolman_ks.
Checks palindromic string WITHOUT reversing it.
Same logic can be used to build this program in other languages.
*/
/*
Logic: In a palindromic string, the 1st and last, 2nd and 2nd last, and so
on characters are equal.
Return false from the function if any of these matches, i.e (1st and last),
(2nd and 2nd last) are not equal.
*/
#include <iostream>
using namespace std;
bool checkPalindromicString(string text){
int counter_1 = 0; //Place one counter at the start.
int counter_2 = text.length() - 1; //And the other at the end.
//Run a loop till counter_2 is not less that counter_1.
while(counter_2 >= counter_1){
if(text[counter_1] != text[counter_2]) return false; //Check for match.
//Note: Execution of a function is halted as soon as a value is returned.
else{
++counter_1; //Move the first counter one place ahead.
--counter_2; //Move the second character one place back.
}
}
return true;
/*
Return true if the loop is not broken because of unequal characters and it
runs till the end.
If the loop runs till the condition specified in it, i.e
(counter_2 >= counter1), that means all matches are equal and the string is
palindromic.
*/
}
//Implementation of the function.
int main(){
cout << checkPalindromicString("racecar") << endl; //Outputs 1 (true).
cout << checkPalindromicString("text") << endl; //Outputs 0 (False).
if(checkPalindromicString("lol")){
cout << "#lolman_ks";
}
//Outputs #lolman_ks.
return 0;
}
//I hope this would be useful to you all, please promote this answer if it is.
//#lolman_ks