Boolean

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Overview

Boolean is a logical datatype. 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.

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

Ouputs:
FALSE
TRUE
FALSE
TRUE
tooLarge is true
TRUE

See also

Data Types
Simple Data Types Boolean | Byte | Cardinal | Char | Currency | Extended | Int64 | Integer | Longint | Pointer | Real | Shortint | Smallint | Word
Complex Data Types Array | Class | Record | Set | String