Difference between revisions of "Boolean"
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== Overview == | == Overview == | ||
| − | '''Boolean''' is a logical | + | '''Boolean''' is a logical [[Data_type|data type]]. Data of type boolean has one of only two values, either [[True|<code>true</code>]] or [[False|<code>false</code>]]. A boolean [[Variable|variable]] is 1 byte in size. |
| − | The | + | The <code>true</code> value can be assigned directly to a boolean variable or from the result of a comparison or test that was successful (<code>true</code>). Similarly the <code>false</code> value can be assigned directly or from the result of a comparison or test that was not successful (<code>false</code>). |
| + | The [[Write]]() and Writeln() [[Procedure|procedures]] will print a [[String|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|if statement]]. The WriteStr() procedure can be used to store a string literal representing a boolean variable's value in a string variable. | ||
<syntaxhighlight> | <syntaxhighlight> | ||
| + | program booleantest; | ||
var | var | ||
tooLarge : Boolean = false; | tooLarge : Boolean = false; | ||
| − | boolString : ShortString; | + | boolString : ShortString; |
begin | 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 | + | end. |
</syntaxhighlight> | </syntaxhighlight> | ||
| + | |||
Ouputs:<br/> | Ouputs:<br/> | ||
| − | '''FALSE''' | + | '''FALSE''' |
| − | '''TRUE''' | + | '''TRUE''' |
| − | '''FALSE''' | + | '''FALSE''' |
| − | '''TRUE''' | + | '''TRUE''' |
| − | '''tooLarge is true''' | + | '''tooLarge is true''' |
| − | '''TRUE''' | + | '''TRUE''' |
== See also == | == See also == | ||
Revision as of 07:06, 16 January 2019
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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.Ouputs:
FALSE TRUE FALSE TRUE tooLarge is true TRUE
See also
| simple data types |
|
|---|---|
| complex data types |
