Difference between revisions of "Boolean"

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Revision as of 22:28, 20 August 2020

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Overview

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


navigation bar: data types
simple data types

boolean byte cardinal char currency double dword extended int8 int16 int32 int64 integer longint real shortint single smallint pointer qword word

complex data types

array class object record set string shortstring