Boolean

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Overview

The simple type boolean is a logical data type. Data of type boolean has one of only two values, either true or false. A boolean variable is 1 byte in size.

The true value can be assigned directly to a boolean variable or from the result of a comparison or test that was successful (true). Similarly the false value can be assigned directly or from the result of a comparison or test that was not successful (false). The Write() and Writeln() procedures will print a string that corresponds to the value of a boolean variable (either "TRUE" or "FALSE"). A Boolean variable can be used as the expression in an if statement. The WriteStr() procedure can be used to store a string literal representing a boolean variable's value in a string variable.

program booleantest;
var
    tooLarge   : Boolean = false;
    boolString : ShortString;
begin
  Writeln(tooLarge);
  tooLarge := (0 = 0);
  Writeln(tooLarge);
  tooLarge := (3 > 5);
  Writeln(tooLarge);
  tooLarge := true;
  Writeln(tooLarge);
  if tooLarge then
    Writeln('tooLarge is true')
  else
    Writeln('tooLarge is false');
  WriteStr(boolString,tooLarge);
  Writeln(boolString);
end.

Outputs:

FALSE
TRUE
FALSE
TRUE
tooLarge is true
TRUE

See also

• Boolean Expressions