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;