Validating function - c++

Question

My question is how do I validate the data for getTestScore function? Need the program to tell the user invalid data, please enter a score in between 0 and 100 in the event that they put in a negative number or number over 100. Thanks.
#include <iostream>
using namespace std;
//function prototypes
float getTestScore();
float calcAverage(float score1, float score2, float score3);
int main()
{
float s1, s2, s3; //these variables are used to store test scores
float average;
//call getTestScore function to get the test scores
s1 = getTestScore();
s2 = getTestScore();
s3 = getTestScore();
//call calcAverage to calculate the average of three test scores
average = calcAverage(s1, s2, s3);
//display the average
cout << "average of three test scores(" << s1 << "," << s2 << "," << s3 << ")is" << average << endl;
return 0;
}
//function definitions/implementation getTestScore function gets a test score from the user and
//validates the score to make sure the value is between 0 and 100. if score is out of range
//getTestScore function allows the user to re-enter the score. This function returns a valid score
// to the caller function
float getTestScore()
{
float score = 0;
do
{
cout << "Enter test score: " << endl;
cin >> score;
} while (!(score >= 0 && score <= 100));
return score;
}
// calcAverage function calculates and returns the average of the three test scores passed to
//the function as input.
float calcAverage(float score1, float score2, float score3)
{
float average;
average = (score1 + score2 + score3) / 3;
return average;
}

Answer 1

You can change the while loop to this:
float getTestScore()
{
float score = 0;
while ((cout << "Enter test score: ")
&& (!(cin >> score) || score < 0 || score > 100)) {
// This part only gets executed on invalid input
cout << "invalid data, please enter a score in between 0 and 100 ";
cin.clear();
cin.ignore(numeric_limits<streamsize>::max(), '\n');
}
return score;
}

Answer 2

By using a "Do-While" your executing the block of code at least once before checking the input.
The first input is therefore not checked by your condition:
while (!(score >= 0 && score <= 100));
Using a standard while loop and therefore checking this condition before hand should resolve your problem.