my code is working perfectly as shown on test cases but why is it failing every test case.?

Question

reversing a string. [code coach: extra terrestrial]
https://code.sololearn.com/crLA30filGNt/?ref=app

Answer 1

// Try it

while(max>0)
{
std::cout << st1[max-1];
max--;
}

Answer 2

it is working perfectly now , but what was the problem before, can you plz explain it.

Answer 3

sahil somyani ,

int max = st1.length(); // to get the array length

std::cout << st1[max-1]; // to get the last index is "length - 1"