Help needed in debugging(isPalindrome)

#1

#include<bits/stdc++.h>
using namespace std;

bool isPalindrome(char str[], int l, int r)
{
if(strlen(str) == 1)
return true;
if(str[l] == str[r] && strlen(str)==2){
return true;}
else if(str[l] == str[r]){
char res[r-1];
for(int i = l+1, j = 0; i <= r-1; i++, j++)
res[j] += str[i];
isPalindrome(res, 0, strlen(res)-1);
}
return false;
}
int main()
{
int n;
cin >> n;
cin.get();
char str[n];
for(int i = 0; i < n; i++)
cin >> str[i];

bool ans = isPalindrome(str, 0, strlen(str)-1);
if(ans)
    cout << "true" << endl;
else
    cout << "false" << endl;
return 0;

}
Could you tell me where I am going wrong in the recursion part?

#3

@utkarshvashisth94 you cannot use strlen function here. So I rewrote you code and handling everything in terms of n and made your isPalindrome function accept 4 parameters. Please see https://ide.codingblocks.com/s/191589 . If you have any further queries please feel free to ask.
Also in line 15 I added return infront of isPalindrome, you were making that mistake in your code, so it was eventually going to return false for every case
And you had to do res[j]=str[i] and not res[j]+=str[i]

#4

@utkarshvashisth94 If you don’t have any further doubts ,please mark this as resolved.

#5

#include<bits/stdc++.h>
using namespace std;

bool isPalindrome(char str[], int l, int r)
{
if(strlen(str) == 1)
return true;
if(str[l] == str[r] && strlen(str)==2){
return true;}
else if(str[l] == str[r]){
char res[r-1];
for(int i = l+1, j = 0; i <= r-1; i++, j++)
res[j] += str[i];
isPalindrome(res, 0, strlen(res)-1);
}
return false;
}
int main()
{
int n;
cin >> n;
cin.get();
char str[n];
for(int i = 0; i < n; i++)
cin >> str[i];

bool ans = isPalindrome(str, 0, strlen(str)-1);
if(ans)
    cout << "true" << endl;
else
    cout << "false" << endl;
return 0;

}

#6

this is the same code as above, please refer to the answer provided above and if you have any query, ask about the same.