为什么我的程序无法打印出正确的余数？

Question

I need help so bad. I've been working on this homework assignment for 2 hours and i can't get my logic straight. We are not allowed to use the % or / operators but we must divide and find the remainder just by subtracting- my program prints out the division part but not the remainder. Any clues guys? I'm learning and i know it's a small error but i can't figure it out. I've checked all of the other questions that are similar but they weren't of any help. Thank you all.

this is my program so far

import java.util.Scanner;

public class assignment4 {
public static void main(String args[]) {
    Scanner inputReader = new Scanner(System.in);

    int multiplicand, multiplier;
    double dividend, divisor, countDivisor, countDividend, remainder;
    int total=0, total2 = 0, countMult;

    System.out.print("Enter a multiplican: ");
    multiplicand = inputReader.nextInt();
    System.out.print("Enter a multiplier: ");
    multiplier = inputReader.nextInt();

    countMult = multiplier;
    while(multiplier > 0) {

        total = total + multiplicand;
        multiplier--;
    }

    System.out.println(multiplicand + " times " + countMult + " equals " + total );

    System.out.print("Enter a dividend: ");
    dividend = inputReader.nextInt();
    System.out.print("Enter a divisor: ");
    divisor = inputReader.nextInt();

    countDivisor = divisor;
    countDividend = dividend;
    while(dividend >= 0) {

        dividend = dividend - divisor;
        divisor--;
    }

    remainder =  divisor - 1;
    System.out.print(countDividend + " divided by " + countDivisor + " equeals " + divisor + " with a remainder of " + remainder);
}

}

Answer 1

your while loop is iterating while the dividend is >=0

example dividend = 10 and divisor = 3

looping

10 - 3 = 7 // >= 0 true
7 - 3 = 4 // >= 0 true
4 - 3 = 1 // >= 0 true it should stop here because dividend is < divisor
1 - 3 = -2 // >= 0 false

this would do the division

while(dividend >= divisor){
  dividend -= divisor;
  // count your result ++
}  
System.out.println(dividend);//this is the remainder

Answer 2

Everything you have is fine exception your while loop and your computation for remainder:

Here's a helpful adjustment:

int result = 0;
while (dividend >= divisor)
{
   dividend = dividend - divisor;
   result = result + 1;
}
remainder = dividend;
System.out.print(countDividend + " divided by " + countDivisor + " equals " + integer_result + " with a remainder of " + remainder);

By the way, your program doesn't handle negative numbers too well. You should consider fixing that bug before submitting your homework.

Answer 3

You are doing it entirely wrong, and your prof is gonna ding you bad.

To multiply you shift and add:

        1 0 1 0 -- bits A B C D  == 10  
      x 1 1 0 0 -- bits E F G H  == 12

D is zero, so the first cycle (multiply EFGH by zero) results in

        0 0 0 0 

Shift EFGH left one

      1 1 0 0 0

Bit C is 1 so the result is

      1 1 0 0 0 

Shift EFGH left one

    1 1 0 0 0 0

Bit B is 0 so no change

Shift EFGH left one

  1 1 0 0 0 0 0

Bit A is 1 so add

  1 1 0 0 0 0 0
   +  1 1 0 0 0
  -------------
  1 1 1 1 0 0 0

Division is the same thing, only backwards.