Difference between revisions of "Boolean"

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m (typo)
(show assignment to boolean variable)
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'''Boolean''' is a logical datatype. Data of type boolean has one of only two values, either [[True|true]] or [[False|false]]. A Boolean variable is 1 byte in size.
 
'''Boolean''' is a logical datatype. Data of type boolean has one of only two values, either [[True|true]] or [[False|false]]. A Boolean variable is 1 byte in size.
  
−
The '''true''' value is used to indicate a comparison or test was successful; the '''false''' value is used to indicate a comparison or test was not successful.
+
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.
  
 
<syntaxhighlight>
 
<syntaxhighlight>
−
write (3 > 5)
+
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
 
</syntaxhighlight>
 
</syntaxhighlight>
−
'''FALSE'''
+
Ouputs:<br/>
−
 
+
'''FALSE'''<br/>
−
<syntaxhighlight>
+
'''TRUE'''<br/>
−
write (0 = 0);
+
'''FALSE'''<br/>
−
</syntaxhighlight>
+
'''TRUE'''<br/>
−
'''TRUE'''
+
'''tooLarge is true'''<br/>
 +
'''TRUE'''<br/>
  
 
== See also ==
 
== See also ==

Revision as of 09:06, 24 June 2016

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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. 

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


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




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