Assignment operators

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Assignment operators assign a value to a variable. The most familiar assignment operator is the equals sign "=", however there are other assignment operators that act as "shortcuts" for several of the mathematical operators.

General Syntax and Usage

The basic assignment operator assigns the value of the expression on the right-hand side of the operator to the variable on the left-hand side. For instance,

x = 12 + 3;

assigns the value of 12 + 3 (which is of course 15) to the variable x. The complexity of the expression on the right-hand side of the operator is practically unlimited. The final value of the right-hand expression should be of the same data type as the variable on the left-hand side of the operator. For example, if the expression on the right ends up being a boolean true or false while the variable on the left is an integer or float, you may get unexpected results - or your script won't compile at all. See typecasting for additional details.

Due to the nature of the assignment operator, the left-hand operand must be a variable or an editable property (such as Link->HP, Link's hitpoints). You cannot use the assignment operator in statements like,

12 + 3 = x;

or

x + 2 = 3 - y;

These are invalid and will not compile.

Note, however, that the variable on the left-hand side of the operator may also appear in the right-hand expression. Keep in mind that the right-hand side expression is always evaluated first, and then the result is stored in the variable on the left-hand side. For instance, the two statements

x = 10;
x = x + 10;

are executed as follows:

  1. in the first statement, a value of 10 is assigned to x.
  2. in the second statment, 10 is added to x for a final value of 20, and then that value of 20 is stored back into x.

Variants of the Assignment Operator

Often times you will need to modify the value of a variable (or built-in property, like Link's hitpoints) and store the result back into the same variable or property. Using just the basic assignment operator, you would write such an operation as follows:

// Add 16 hitpoints to Link's hitpoints.
Link->HP = Link->HP + 16;

Variants of the assignment operator can shorten such operations. In the previous example, the Additive Assignment Operator could be used as follows:

// Add 16 hitpoints to Link's hitpoints.
Link->HP += 16;

Examples of the assignment operator variants are given below, but in all cases the variant is simply the desired operator (+, -, *, etc.) followed directly by the equals sign.

Additive Assignment Operator

The additive assignment operator adds the expression on the right-hand side of the operator to the value of the variable on the left-hand side. For example,

Link->HP += 16;

is the same as

Link->HP = Link->HP + 16;

Subtractive Assignment Operator

The subtractive assignment operator subracts the expression on the right-hand side of the operator from the value of the variable on the left-hand side. For example,

Link->HP -= 16;

is the same as

Link->HP = Link->HP - 16;

Multiplicative Assignment Operator

The multiplicative assignment operator multiplies the the value of the variable on the left-hand side by the expression on the right-hand side. For example,

Link->HP *= 2;

is the same as

Link->HP = Link->HP * 2;

Divisive Assignment Operator

The divisive assignment operator divides the the value of the variable on the left-hand side by the expression on the right-hand side. Bare in mind that division by 0 is undefined. For example,

Link->HP /= 2;

is the same as

Link->HP = Link->HP / 2;

See Also