// Demonstrating the use of a while loop with a sentinel
// condition.
// Sasha Vassar Week 2, Lecture 4

/*
Using a while loop allows us to repeat certain pieces of 
code. 

//1. Initialise loop control variable
    while (condition) { //2. Test the condition         
                         against the loop control variable

//3. Update loop control variable (last statement of while loop
}

*/

#include <stdio.h>

// Problem: I want to read in some scores until a negative number has been 
// entered, and I want to only add the even scores up. 

int main (void) {
  
  
    int score;
    int sum = 0;
    //1. Read in some scores 
    //2. Stop reading when a negative number has been read)
    //3. Add the even scores up
    //   - Check if the entered score is an even number, if it is add it to the sum
    
    //1. Set my loop control variable
    int endloop_flag = 0; 
  
    while (endloop_flag == 0) { //2. Check the condition with that variable
        printf("Please enter a score to add to the sum: ");
        scanf("%d", &score);
        //Is this number that I have read in positive or negative?
        if (score >= 0) {
            //Is this score an even number? IF
            if (score % 2 == 0) {
                sum = sum + score;
                printf("The sum is now %d\n", sum);
            }
        } else {
            endloop_flag = 1;
        }   
    }
    printf("The final sum of scores is %d\n", sum);
    return 0;
}