Assignment Statements

In BASIC, the “=” character represents both the equality operator and the assignment operator – it all depends on where the “=” is found. The is different from C, which has unique operators for equality (“==”) and assignment (“=”). Consider these examples:

IF A = 5 THEN
A = 5
A = B = 5

The first example contains equality operator and the second example has the assignment operator. In the third example, does the statement contain two assignment operators (like C) or does it contain an assignment operator and an equality operator? In GW-Basic, SmallBASIC, FreeBASIC and QuickBASIC, it is the latter assigning A to a true or false value depending on where B is equal to 5 or not.

Multiple assignments can be convenient so they will be supported like in the third example above. But it can also be convenient to be able to use the equality operator (or any relational operator) in expressions beyond conditional expressions (in IF, WHILE, UNTIL, etc. statements). Two forms of multiple assignments will be supported:

Variable1 = Variable2 = Variable3 = Expression
Variable1 , Variable2 , Variable3 = Expression

For the first form, the “=” characters will interpreted as assignment operators until the expression starts, in other words, once there is a another operator including an expression in parentheses:

Variable1 = Variable2 = (Variable3 = Expression)
Variable1 = Variable2 = Variable3 + Expression1 = Expression2

Here Variable1 and Variable2 will be assigned to a true or false value depending on whether Variable3 is equal to the Expression in the first example of Variable3 + Expression1 is equal to Expression2 in the second example (the third “=” in both examples is the equality operator).