Compound assignment statements
This topic describes the syntax and parameters for compound assignment statements.
Syntax
Parameters
- reference
- Specifies the target to be given the assignment
- compound assignment operator
- Specifies the operator that is applied to the reference and the evaluated expression before the assignment is made. Table 1 lists the compound assignment operators allowed in compound assignments.
- expression
- Specifies an expression that is evaluated and possibly converted.
For information about area assignment, see Area data and attribute.
| Compound assignment operator | Meaning |
|---|---|
| += | Evaluate expression, add and assign |
| -= | Evaluate expression, subtract and assign |
| *= | Evaluate expression, multiply and assign |
| /= | Evaluate expression, divide and assign |
| |= | Evaluate expression, or and assign |
| &= | Evaluate expression, and and assign |
| ∥= | Evaluate expression, concatenate and assign |
| **= | Evaluate expression, exponentiate and assign |
| ¬= or <> | Evaluate expression, exclusive-or and assign |
The operator is applied to the target and source first, and then what results is assigned to the target.
See the following example:
X += 1 |
is the same as | X = X+(1) |
X *= Y+Z |
is the same as | X = X*(Y+Z) |
But the following statements are not equivalent:
X *= Y+Z |
is not equivalent to | X = X*Y+Z |
In a compound assignment, any subscripts or locator expressions specified in the target variable are evaluated only once.
If f is a function and X is
an array, the following statements are not equivalent:
X(f()) += 1 |
is not equivalent to | X(f()) = X(f())+1 |
The function f is called only once.