I always get no output after running my C and C++ code on challenges, like this one below. Why?

Question

#include <iostream>
#include <string>
using namespace std;

int main() {
string str;
cin >> str;
int i = 0, tmpG, tmpM, tmpT;
int len = str.length();
cout << str[2];
while (i <= len)
{
if (str[i] == 'G')
{
tmpG = i;
}
else if (str[i] == 'T')
{
tmpT = i;
}
else if (str[i] == '

Answer 1

Just remove the:
else{
continue;
}
this makes the loop an infinite loop so it gives no output
and loop should be:
while(i<len)

Answer 2

No 1 rule in codind: The computer doesn't make a mistake it's the user.

Answer 3

That's what a friend told me.