//* How long to stay in a loop - 4 examples *

// How long to stay in a loop: loop type #1
#include <stdio.h>

int main() {

    int cnt;
    double sum=0.0;         // remember to initialize the sum

    printf("Please enter the number of data items ");
    scanf("%d", &cnt);      // read number of numbers

    printf("Please enter the data one by one:" << endl;
    for (int i=1; i<=cnt; i++) {
        double x;
        scanf("%lf", &x);   // read next number available
        sum+=x;
    }

    printf("The average number is %lf\n", sum/cnt);
    return(0);
}


// How long to stay in a loop: loop type #2
#include <stdio.h>

int main() {

    int    cnt=0;           // remember to initialize the count   
    double sum=0.0;         // remember to initialize the sum

    printf("Please enter the data one by one followed by a negative number:\n");
    for (;;) {
        double x;
        scanf("%lf", &x);   // read next number available
        if (x<0) break;
        sum+=x;
        cnt++;
    }
    // break goes here

    printf("The average number is %lf\n", sum/cnt);
    return(0);
}


// How long to stay in a loop: loop type #3
#include <stdio.h>

int main() {

    int    cnt=0;           // remember to initialize the count   
    double sum=0.0;         // remember to initialize the sum

    for (;;) {
        printf("Please enter the next data item: ");
        double x;
        scanf("%lf", &x);   // read next number available
        sum+=x;
        cnt++;

        char ch;
        printf("Continue? (y/n)");
        scanf("%c", &ch);
        if (ch=='n') break; 
        // single character goes in single quotes - 'n'
    }
    // break goes here

    printf("The average number is %lf\n", sum/cnt);
    return(0);
}


// How long to stay in a loop: loop type #4
#include <stdio.h>

int main() {

    int    cnt=0;               // remember to initialize the count   
    double sum=0.0;             // remember to initialize the sum

    printf("Please enter the data one by one followed by a letter q:\n");
    for (;;) {
        double  x;
        int     r;
        r = scanf("%lf", &x);   // read next number available
        if (r==0 || r==EOF) break;  // exit if non-numeric data encountered - read failed
        sum+=x;
        cnt++;
    }
    // break goes here

    printf("The average number is %lf\n", sum/cnt);
    return(0);
}