Well done for doing it without the use of the erase() function. You've basically implemented it yourself which is good practice

Stunning..!

I mean even when I write one line of code in the function such as, return true or return false, without anything alse, it still returns number 1(in the case of true) or 0(in the case) not boolen value true or false. when I directly return true or false from code, the actual result is 1 or 0. I could solve this problem but becuase of this, I can not complete this kata.

It's a problem with your code, not a kata issue, if you return in both cases inside your loop, you're only testing the first char.

I am using c++ version 14. the function always return 0 or 1. I driectly returned other values such as boolen(true or false), string, and int. it still show actual result 0 or 1. Any information?