isByte

isByte(): Boolean;

The isByte method of the String primitive type returns true if the receiver represents a valid byte value; that is, in the range zero (0) through 255; otherwise, it returns false.

The following example shows the use of the isByte method.

vars
    stringValue : String;
begin
    stringValue := '+123';
    write stringValue.isByte;   // Outputs true
    stringValue := '+321';
    write stringValue.isByte;   // Outputs false
end;