Difference between revisions of "If and Then"
From Lazarus wiki
Jump to navigationJump to searchm (link Case) |
(usage of Template:Translate; eliminate excessive space) |
||
Line 1: | Line 1: | ||
− | {{ | + | {{Translate}} |
− | |||
The <syntaxhighlight lang="pascal" enclose="none">if</syntaxhighlight> [[Keyword|keyword]] precedes a condition, must be followed by <syntaxhighlight lang="pascal" enclose="none">then</syntaxhighlight> and a statement. | The <syntaxhighlight lang="pascal" enclose="none">if</syntaxhighlight> [[Keyword|keyword]] precedes a condition, must be followed by <syntaxhighlight lang="pascal" enclose="none">then</syntaxhighlight> and a statement. | ||
The statement may optionally be followed by [[Else|<syntaxhighlight lang="pascal" enclose="none">else</syntaxhighlight>]] and another statement. | The statement may optionally be followed by [[Else|<syntaxhighlight lang="pascal" enclose="none">else</syntaxhighlight>]] and another statement. | ||
− | |||
== <syntaxhighlight lang="pascal" enclose="none">If then</syntaxhighlight> == | == <syntaxhighlight lang="pascal" enclose="none">If then</syntaxhighlight> == | ||
− | |||
<syntaxhighlight lang="pascal"> | <syntaxhighlight lang="pascal"> | ||
if condition | if condition | ||
Line 17: | Line 14: | ||
<syntaxhighlight lang="pascal" enclose="none">false_statement</syntaxhighlight> is executed if <syntaxhighlight lang="pascal" enclose="none">condition</syntaxhighlight> evaluates to <syntaxhighlight lang="pascal" enclose="none">false</syntaxhighlight>. | <syntaxhighlight lang="pascal" enclose="none">false_statement</syntaxhighlight> is executed if <syntaxhighlight lang="pascal" enclose="none">condition</syntaxhighlight> evaluates to <syntaxhighlight lang="pascal" enclose="none">false</syntaxhighlight>. | ||
A compile-time error occurs if the type of <syntaxhighlight lang="pascal" enclose="none">condition</syntaxhighlight> does not evaluate to a <syntaxhighlight lang="pascal" enclose="none">boolean</syntaxhighlight> value. | A compile-time error occurs if the type of <syntaxhighlight lang="pascal" enclose="none">condition</syntaxhighlight> does not evaluate to a <syntaxhighlight lang="pascal" enclose="none">boolean</syntaxhighlight> value. | ||
− | |||
=== Multiple statements in <syntaxhighlight lang="pascal" enclose="none">if then</syntaxhighlight> branch === | === Multiple statements in <syntaxhighlight lang="pascal" enclose="none">if then</syntaxhighlight> branch === | ||
− | |||
If you need two or more statements for <syntaxhighlight lang="pascal" enclose="none">true_statement</syntaxhighlight> or <syntaxhighlight lang="pascal" enclose="none">false_statement</syntaxhighlight>, enclose them within a [[Begin|<syntaxhighlight lang="pascal" enclose="none">begin</syntaxhighlight>]] … [[End|<syntaxhighlight lang="pascal" enclose="none">end</syntaxhighlight>]] [[Block]] (compound statement). | If you need two or more statements for <syntaxhighlight lang="pascal" enclose="none">true_statement</syntaxhighlight> or <syntaxhighlight lang="pascal" enclose="none">false_statement</syntaxhighlight>, enclose them within a [[Begin|<syntaxhighlight lang="pascal" enclose="none">begin</syntaxhighlight>]] … [[End|<syntaxhighlight lang="pascal" enclose="none">end</syntaxhighlight>]] [[Block]] (compound statement). | ||
Line 31: | Line 26: | ||
end; | end; | ||
</syntaxhighlight> | </syntaxhighlight> | ||
− | |||
== See also == | == See also == | ||
− | |||
* Official documentation: [https://www.freepascal.org/docs-html/ref/refsu57.html Reference guide: § “The <syntaxhighlight lang="pascal" enclose="none">If..then..else</syntaxhighlight> statement”] | * Official documentation: [https://www.freepascal.org/docs-html/ref/refsu57.html Reference guide: § “The <syntaxhighlight lang="pascal" enclose="none">If..then..else</syntaxhighlight> statement”] | ||
* [[IF]], Tao Yue, Object Pascal Introduction | * [[IF]], Tao Yue, Object Pascal Introduction |
Revision as of 14:44, 12 October 2018
Template:Translate
The if
keyword precedes a condition, must be followed by then
and a statement.
The statement may optionally be followed by else
and another statement.
If then
if condition
then true_statement
else false_statement;
condition
is a boolean
expression that evaluates to true
xor false
.
true_statement
is executed if condition
evaluates to true
.
false_statement
is executed if condition
evaluates to false
.
A compile-time error occurs if the type of condition
does not evaluate to a boolean
value.
Multiple statements in if then
branch
If you need two or more statements for true_statement
or false_statement
, enclose them within a begin
… end
Block (compound statement).
if boolean_condition then
begin
statement_zero;
statement_one;
statement_two;
end;
See also
- Official documentation: Reference guide: § “The
If..then..else
statement” - IF, Tao Yue, Object Pascal Introduction
- If statement and semicolon
case
Keywords: begin — do — else — end — for — if — repeat — then — until — while