Test Puzzle #1

Static testing is very important especially on the beginning of the project, but also important are code reviews during implementation both the product and the test scripts. On this blog will be some test puzzles so you can try by yourself catch some mistakes in  implementation in various, but popular, programming languages. 

Test this C++ code:

Difficulty: 1/4

#include <iostream>
 
using namespace std;
 
int main() {
        
        for(i = 0; i < 9; i++)
        {
                cout << i << endl;
        }
        return 0;
}

Answer: "i" is not declared. See also this code on Ideone.