Sử dụng struct để biểu diễn phân số

Yêu cầu:

– Tính tổng, hiệu, tích, thương 2 phân số
– Rút gọn phân số
– Quy đồng 2 phân số
– So sánh 2 phân số

/***************************Complex****************************
* Author: vncoding
* Date : 12/01/2016
***************************************************************/
#include <stdio.h>
#include <conio.h>

typedef struct FraTag
{
    int num;
    int den;
}FRACTION;

int grst_comm_div(int a, int b);
int lst_comm_mult(int a, int b);
void fra_import(FRACTION* fra);
void fra_show(FRACTION fra, char name);
FRACTION fra_operator(FRACTION firstFra, FRACTION secondFra, char op);
FRACTION fra_reduce(FRACTION fra);

void main()
{
    int sel;
    char c;
    FRACTION fract[2];
    FRACTION resFra;
    fra_import(&fract[0]);
    fra_show(fract[0], '1');
    fra_import(&fract[1]);
    fra_show(fract[1], '2');

    do
    {
        printf("\n\n1. Cong 2 phan so: C = A+B");
        printf("\n2. Tru 2 phan so: C = A-B");
        printf("\n3. Nhan 2 phan so: C = A*B");
        printf("\n4. Chia 2 phan so: C = A/B");
        printf("\nBan chon: ");
        scanf("%d", &sel);

        switch(sel)
        {
        case 1:
            resFra = fra_operator(fract[0], fract[1], '+');
            fra_show(resFra, '3');
            break;
        case 2:
            resFra = fra_operator(fract[0], fract[1], '-');
            fra_show(resFra, '3');
            break;
        case 3:
            resFra = fra_operator(fract[0], fract[1], '*');
            fra_show(resFra, '3');
            break;
        case 4:
            resFra = fra_operator(fract[0], fract[1], '/');
            fra_show(resFra, '3');
            break;
        }
        printf("\nBan co muon tiep tuc ko: (y/n)?");
        fflush(stdin);
        c = getchar();
    }
    while( c == 'y' || c == 'Y');
    getch();
}

// Ham tim USCLN
int greatest_common_divisor(int a, int b)
{
    if(a == 0 && b == 0)
        return -1;
    else
        return (b == 0)? a : greatest_common_divisor(b, a%b);
}

// Ham tim BSCNN
int lowest_common_multiple(int a, int b)
{
    if(a == 0 || b == 0)
        return -1;
    else
        return (a*b/greatest_common_divisor(a, b));
}

// Ham nhap phan so
void fra_import(FRACTION* fra)
{
    printf("\nNhap vao tu so: ");
    scanf("%d", &fra->num);
    do
    {
        printf("\nNhap vao mau so: ");
        scanf("%d", &fra->den);
    }while(fra->den == 0);
}

// Ham tinh +, -, *, / 2 phan so
FRACTION fra_operator(FRACTION firstFra, FRACTION secondFra, char op)
{
    FRACTION resFra;
    int lowest_common_den;
    int greatst_common_div;
    switch(op)
    {
    case '+':
        resFra.num = firstFra.num * secondFra.den + 
        secondFra.num * firstFra.den;
        resFra.den = firstFra.den * secondFra.den;
        resFra = fra_reduce(resFra);
        break; 
    case '-':
        resFra.num = firstFra.num * secondFra.den - 
        secondFra.num * firstFra.den;
        resFra.den = firstFra.den * secondFra.den;
        resFra = fra_reduce(resFra);
        break;
    case '*':
        resFra.num = firstFra.num * secondFra.num;
        resFra.den = firstFra.den * secondFra.den;
        resFra = fra_reduce(resFra);
        break;
    case '/':
        resFra.num = firstFra.num * secondFra.den;
        resFra.den = firstFra.den * secondFra.num;
        resFra = fra_reduce(resFra);
        break;
    default:
        printf("\nToan tu khong hop le");
    }
    return resFra;
}

// Ham rut gon phan so
FRACTION fra_reduce(FRACTION fra)
{
    FRACTION resFra;
    int greatest_common_div = greatest_common_divisor(fra.num, fra.den);
    resFra.num = fra.num/greatest_common_div;
    resFra.den = fra.den/greatest_common_div;
    return resFra;
}

// Show fraction
void fra_show(FRACTION fra, char name)
{
    printf("\nPS(%c) = %d/%d", name, fra.num, fra.den);
}

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