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Assignments
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Assignments give a value to a variable, replacing any previous value the variable might have had:
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Assignments
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In addition to the standard Pascal assignment operator (:=), which simply replaces the value of the variable with the value resulting from the expression on the right of the := operator, Free Pascal supports some C-style constructions. All available constructs are listed in table (13.1).
| Assignment | Result |
| a += b | Adds b to a, and stores the result in a. |
| a -= b | Subtracts b from a, and stores the result in a. |
| a *= b | Multiplies a with b, and stores the result in a. |
| a /= b | Divides a through b, and stores the result in a (only for floats, not integers). |
For C-like assignments, the $COPERATORS directive must be enabled or the -Sc command-line switch must be specified when compiling. These constructions are just for typing convenience and generate the same code.
Remark
Here is an example with some valid assignment statements:
var
Done: Boolean;
S: String;
X, Y: Double;
begin
Done:=False or (1=2);
S:='text';
X:=X+Y;
{$COPERATORS ON}
X+=Y; // same as X:=X+Y
X/=2; // same as X:=X/2
end.
Keeping in mind that the dereferencing of a typed pointer results in a variable of the type the pointer points to, the following are also valid assignments:
var L : ˆLongint; P : PPChar; begin Lˆ:=3; Pˆˆ:='A'; end.
Note the double dereferencing in the second assignment.