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書名： Unreal Development Kit Game Programming with UnrealScript：Beginner's Guide
作者名： Rachel Cordone
本章字數： 364字
更新時間： 2021-08-27 11:59:08

Time for action – Math!

As an example, take a look at this code.

var float Float1, Float2;
var int Int1;

function PostBeginPlay()
{
    Float2 = Int1 / Float1;
    'log("Float2:" @ Float2);
}

defaultproperties
{
    Int1=5
    Float1=2.0
}

We can divide an int by a float or vice versa, and we get the result we expect:
```
[0008.10] ScriptLog: Float2: 2.5000
```
However, if we divide an int by an int and assign it to a float, what would we expect the result to be?
Let's take a look at this code:
```
var float Float1;
var int Int1, Int2;

function PostBeginPlay()
{
    Float1 = Int1 / Int2;
    'log("Float1:" @ Float1);
}

defaultproperties
{
    Int1=5
    Int2=2
}
```
With that it looks like we'd expect the same result. Let's take a look at the log:
```
[0007.66] ScriptLog: Float1: 2.0000
```
When dividing ints, the truncating happens before assigning the result, even if it's a float. Depending on what we're doing this may be what we want, but it's good to keep that in mind.
Two other operators that can be used for simple math are increment ( ++ ) and decrement ( – ).
```
Int1 = 5;
Int1++;
'log("Int1" @ Int1);
```
This would give us 6 in the log.
For vectors and rotators, the arithmetic works with each element of the struct individually. For example, with the following code:
```
var vector Vect1, Vect2, VectResult;

function PostBeginPlay()
{
    VectResult = Vect1 + Vect2;
    'log("VectResult:" @ VectResult);
}

defaultproperties
{
    Vect1=(X=1.0,Y=4.5,Z=12.0)
    Vect2=(X=2.0,Y=4.0,Z=8.0)
}
```
We get the following result in the log:
```
[0007.74] ScriptLog: VectResult: 3.00,8.5,20.00
```
As we can see, each individual element has been worked with separately. X added to X, Y to Y, and Z to Z.
Vectors can also be multiplied or divided by floats and ints. This has the effect of changing the vector's VSize while keeping the direction the same.

What just happened?

The basic arithmetic operators are simple stuff, but when working with different types of variables it's important to remember how they'll respond to the operators.

Modulo

Modulo ( % ) returns the remainder after division. It's a pretty obscure and not commonly used operator, but when needed it can save many lines of code.

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Unreal Development Kit Game Programming with UnrealScript：Beginner's Guide

Time for action – Math!

What just happened?

Modulo