Assignment Operations

Variables get values by means of assignment statements. Simple assignment statements are of the form:

<nvar> = <nexp>
<svar> = <sexp>

The special form of the statement allows BASIC! to infer the command. The implied command is LET.

Let

The original Basic language used the command, LET, to denote an assignment operation as in:

LET <nvar> = <nexp>

BASIC! also has the LET command but it is optional. If you use other programming languages, it may look strange to you, but there are two reasons you might use LET.

First, you must use LET if you want to have a variable name start with a BASIC! keyword. Such keywords may not appear at the beginning of a new line. The statement:

Letter$ = "B"

is seen by BASIC! as

LET ter$ = "B"

If you really want to use Letter$ as a variable, you can safely use it by putting it in a LET statement:

LET Letter$ = "B"

If you do the assignment in a single-line IF statement, you must also use the LET command:

IF 1 < 2 THEN LET letter$ = "B"

Second, assignment is faster with the LET command than without it.

OpEqual Assignment Operations

All of the binary arithmetic and logical operators (+, -, *, /, ^, &, |) may be used with the equals sign (=) to make a single "OpEqual" operator. The combined operator works like this:

var op= expression  is the same as  var = var op (expression)

Here are some examples:

a += 1            is the same as        a = a + 1
a$ += "xyz"        is the same as        a$ = a$ + "xyz"
b /= 5 + 3        is the same as        b = b / (5 + 3)
c ^= log(37) + 1    is the same as        c = c ^ (log(37) + 1)
d *= --d + d--        is the same as        d = d * (--d + d--)
m &= (x$ = y$) | (x$ != z$) is the same as    m = m & ((x$ = y$) | (x$ != z$))