workshop 4B.2

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <conio.h>

void input(int *num, int *den); // input numerator (num) and denominator of a fraction (den)
void display(int num, int den); // display the fraction
void simplify(int *num, int *den); // simplify the fraction

int main() {
    int n, d;
    char choice;

    do {
        printf("1. Input fraction\n\n");
        input(&n, &d);
        printf("\n2. Simplify fraction\n\n");
        display(n, d);
        printf("=\n");
        simplify(&n, &d);
        display(n, d);

        do {
            fflush(stdin);
            printf("Another run <y/n>? ");
            scanf("%c", &choice);
            if (choice != 'n' && choice != 'y') {
                printf("Invalid!\n");
            }
        } while (choice != 'n' && choice != 'y');

        if (choice == 'n') {
            break; // ra khoi do-while(1)
        }
    } while (1);

    return(0);
}

void input(int *num, int *den) {
    char ch;

    /* input & check validation*/
    while (1) // input numrator
    {
        printf("Enter numerator: ");
        fflush(stdin);
        scanf("%d%c", num, &ch);
        if (ch == '\n') {
            break;
        }
        else {
            printf("Invalid numerator, please re-enter!\n");
        }
    }

    ch = '\0';
    while (1) { // input denominator

        printf("Enter denominator: ");
        fflush(stdin);
        scanf("%d%c", den, &ch);
        if (*den != 0 && ch == '\n') {
            break;
        }
        else {
            printf("Invalid denominator, please re-enter!\n");
        }
    }
}

void display(int num, int den) {

    printf("%d/%d\n", num, den);
}

int GCD(int a, int b){  /* giai thuat Euclid */
    while (a!=0) {
        if (a == b) {
            break;
        }
        else {
            if (a>b) {
                a = a-b;
            }
            else {
                b = b-a;
            }
        }
    }
    return a;
}

void simplify(int *num, int *den) {
    int a = GCD( abs(*num), abs(*den));

    *num /= a;
    *den /= a;
}