用減法與位移做除法並取餘數

 #include <stdio.h>

unsigned int division_fun(unsigned int dividend, unsigned int divisor, unsigned int *remainder_ptr)

{

    unsigned int max_num, i, quotient;

    if ((dividend == 0) || (divisor == 0) || (dividend < divisor) || (remainder_ptr == NULL))

    {

        if ((dividend < divisor) && (remainder_ptr))

        {

            *remainder_ptr = dividend;

        }

        return 0;

    }

    for (max_num = 31; max_num > 0; max_num--)

    {

        if (dividend & (1 << max_num))

            break;

    }

    *remainder_ptr = dividend;

    quotient = 0;

    for (i = max_num; i > 0; i--)

    {

        if (*remainder_ptr >= (divisor << i))

        {

            *remainder_ptr -= (divisor << i);

            quotient |= (1 << i);

        }

    }

    if ((i == 0) && (*remainder_ptr >= (divisor << i)))

    {

        *remainder_ptr -= (divisor << i);

        quotient |= (1 << i);

    }

    return quotient;

}

int main()

{

    unsigned int var_a, var_b, quotient, remainder;

    printf("\nPlease input a and b values:");

    scanf("%d %d", &var_a, &var_b);

    printf("\n=============================================\n");

    quotient = division_fun(var_a, var_b, &remainder);

    printf("%d / %d = %d...%d", var_a, var_b, quotient, remainder);

    printf("\n=============================================\n");

    return 0;

}

Please input a and b values:123 3 ============================================= 123 / 3 = 41...0 =============================================

Please input a and b values:12345

132

=============================================

12345 / 132 = 93...69

=============================================