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vb.netdivision
Cyclone
Cyclone

Reputation: 18295

Division in VB.NET

What's the difference between / and \ for division in VB.NET?

My code gives very different answers depending on which I use. I've seen both before, but I never knew the difference.

Upvotes: 18

Views: 31728

Answers (4)

adrianwadey
adrianwadey

Reputation: 1759

10 / 3 = 3.33333333333333, assigned to integer = 3
10 \ 3 = 3, assigned to integer = 3
20 / 3 = 6.66666666666667, assigned to integer = 7
20 \ 3 = 6, assigned to integer = 6

Code for the above:

Dim a, b, c, d As Integer
a = 10 / 3
b = 10 \ 3
c = 20 / 3
d = 20 \ 3

Debug.WriteLine("10 / 3 = " & 10 / 3 & ", assigned to integer = " & a)
Debug.WriteLine("10 \ 3 = " & 10 \ 3 & ", assigned to integer = " & b)
Debug.WriteLine("20 / 3 = " & 20 / 3 & ", assigned to integer = " & c)
Debug.WriteLine("20 \ 3 = " & 20 \ 3 & ", assigned to integer = " & d)

Upvotes: 2

Hans Passant
Hans Passant

Reputation: 941495

There are two ways to divide numbers. The fast way and the slow way. A lot of compilers try to trick you into doing it the fast way. C# is one of them, try this:

using System;

class Program {
    static void Main(string[] args) {
        Console.WriteLine(1 / 2);
        Console.ReadLine();
    }
}

Output: 0

Are you happy with that outcome? It is technically correct, documented behavior when the left side and the right side of the expression are integers. That does a fast integer division. The IDIV instruction on the processor, instead of the (infamous) FDIV instruction. Also entirely consistent with the way all curly brace languages work. But definitely a major source of "wtf happened" questions at SO. To get the happy outcome you would have to do something like this:

    Console.WriteLine(1.0 / 2);

Output: 0.5

The left side is now a double, forcing a floating point division. With the kind of result your calculator shows. Other ways to invoke FDIV is by making the right-side a floating point number or by explicitly casting one of the operands to (double).

VB.NET doesn't work that way, the / operator is always a floating point division, irrespective of the types. Sometimes you really do want an integer division. That's what \ does.

Upvotes: 25

neo2862
neo2862

Reputation: 1526

10 / 3 = 3.333
10 \ 3 = 3 (the remainder is ignored)

Upvotes: 12

Daniel A. White
Daniel A. White

Reputation: 190945

/ Division
\ Integer Division

Upvotes: 7

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