How to use charat function ? charat is giving error in my ide

#1 
#include<iostream>
using namespace std;
/* 
  using integers
bool ispalindrome(int a[],int start,int end)
{  //base case
   if (start>=end)
   {
       return true;
   }
   if (a[start]==a[end])
   {
      return  ispalindrome(a,start+1,end-1);
   }
   
       return false;
   
}
int main(){
    int n;
    cin>>n;
    int a[n];
    for (int i = 0; i < n; i++)
    {
        cin>>a[i];
    }
    cout<<boolalpha<<ispalindrome(a,0,n-1);
    
    return 0;
} */
//using string
#include<iostream>
#include<string>
using namespace std;
bool ispalindrome(string a,int start,int end)
{
     if (start>=end)
     {
        return true;
     }
     if (a.charAt(start)==a.charAt(end))
     {
         return ispalindrome(a,start++,end-1);
     }
     return false;
}
int main(){
    int n;
    cin>>n;
    string a;
    cin>>a;
    bool ans= ispalindrome(a,0,n-1);
    cout<<boolalpha<<ans;
    return 0;
}
#2

hi @sagar_aggarwal, charAt is a java function for c++ there is string::at() function you can use, also there is a small error in your code
instead of return ispalindrome(a,start++,end-1);
it should be return ispalindrome(a,start+1,end-1); 

#include<iostream>
#include<string>
using namespace std;
bool ispalindrome(string a,int start,int end)
{
     if (start>=end)
     {
        return true;
     }
     if (a.at(start)==a.at(end))
     {
         return ispalindrome(a,start+1,end-1);
     }
     return false;
}
int main(){
    int n;
    cin>>n;
    string a;
    cin>>a;
    bool ans= ispalindrome(a,0,n-1);
    cout<<ans<<endl;
    return 0;
}

In case of any doubt feel free to ask :slight_smile:
Mark your doubt as resolved if you got the answer

#3

Thanks abhijeet , actually in the online judgement every input for the string is in new line for example
4
1
2
2
1
therfore it is not giving correct ans how can i solve this? i passed all test cases using int type array

#4

on which platform , this should not be the way of input , they might be taking test cases
i.e first line would be number of testcases,say n and next n lines will have a string , and we have to tell whether it is palindromic for each testcases

#5

check if you are accesible to tjis problem
https://online.codingblocks.com/app/player/68412/content/128068/4913/code-challenge

#6

okay let me check !!

#7

yes abhijeet i will wait :slight_smile:

#8

just take an integer array instead of string , also you have to print true and false so notice that

I have made some small changes to your code

#9

yes i used boolalpha for the same, but why this problem in strings section? also recursion has not been reached till now in the course.

#10

oh i missed that, I used recursion because you used it in your code , this can be done easily using iterative approach , this is a array and string question

refer this:- https://ide.codingblocks.com/s/270003