palindrome function code example

Example 1: check if palindrome

function isPalindrome(str) {
  str = str.toLowerCase();
  return str === str.split("").reverse().join("");
}

Example 2: palindrome

function isPalindrome(sometext) {
  var replace = /[.,'!?\- \"]/g; //regex for what chars to ignore when determining if palindrome
  var text = sometext.replace(replace, '').toUpperCase(); //remove toUpperCase() for case-sensitive
  for (var i = 0; i < Math.floor(text.length/2) - 1; i++) {
    if(text.charAt(i) == text.charAt(text.length - 1 - i)) {
      continue;
    } else {
      return false;
    }
  }
  return true;
}
//EDIT: found this on https://medium.com/@jeanpan/javascript-splice-slice-split-745b1c1c05d2
//, it is much more elegant:
function isPalindrome(str) {
  return str === str.split('').reverse().join(''); 
}
//you can still add the regex and toUpperCase() if you don't want case sensitive

Example 3: palindrome

#include<iostream>
#include<string>
#include<algorithm>
bool IsPalindrome_true_false(const std::string& );

int main ()
{
    
    std::cout<<"Please enter a string:\t";
    std::string str;
    getline(std::cin, str);
    
    // convert the string from uppercase to lowercase 
    int i = 0;
    while(str[i])
    {
        if(str[i] == std::toupper(str[i]) && std::isalpha(str[i]) == 1024)
        str[i]+= 32;
        ++i;
    }
    // looping while string is empty 
    while(str.empty())
    {
        std::cout<<"\nPlease enter a string your string is empty:\t";
        if(!str.empty())
        std::string str;
        getline(std::cin, str);
    }
    
    std::cout<<"\n"<<std::boolalpha<<IsPalindrome_true_false(str)<<std::endl;
    std::cout<<std::endl;

    return 0;
}

// check if string is a palindrome and return true or false 
bool IsPalindrome_true_false(const std::string& str)
{

    int i = 0;                
    int j = str.length() - 1; 

    while(i <= j )
    {   
        
        if(std::isalpha(str[i]) == 0){
            ++i;
            continue;
        }else if(std::isalpha(str[j]) == 0){
            --j;
            continue;
        }   
        if(str[i] != str[j]){
        
           return false;
        }
        ++i;
        --j;
    }  
    return true;
}