Memory & arrays - C++ Question - Program Flow

Hello,

I am trying to write a program to so a user can enter data and store in an array. In my program below, I am using a while statement to validate the data but it executes even when the data is valid. Can anyone tell me why?

Also is there a debugging option where it will show the order that statements in your program are being executed based on certain input?
Thanks I appreciate all help.

int main()
{
int *tests; // Dynamically allocated test score array.
//int total; // Accumulator to calculate average
//int average; // To hold average test score
int numTests; // To hold number of tests
int cntr; // Counter

// Get the number of tests from user.
cout << "How many test scores do you have? ";
cin >> numTests;

//Dynamically allocate array to hold test scores.
tests = new int[numTests];

//Get test scores from user.
for(cntr = 0; cntr < numTests; cntr++)
{
cout << "Enter test score "
<< (cntr + 1 ) << ": ";
cin >> tests[cntr];
}
while(tests[cntr] < 0)
{
cout << "Enter a number greater than 0.";
cin >> tests[cntr];
}
return 0;
}