Difference between revisions of "If and Then"
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{{If}} | {{If}} | ||
− | + | The <code>if</code> [[Keyword|keyword]] precedes a condition, must be followed by <code>[[Then|then]]</code> and a statement. The statement may optionally be followed by <code>[[Else|else]]</code> and another statement. | |
− | == If then == | + | == <code>If then</code> == |
<syntaxhighlight> | <syntaxhighlight> | ||
− | + | if condition | |
− | + | then true_statement | |
− | + | else false_statement; | |
</syntaxhighlight> | </syntaxhighlight> | ||
− | + | <code>condition</code> is a [[boolean]] expression that evaluates to [[True|true]] xor [[False|false]]. | |
− | true_statement is executed if condition evaluates to true. | + | <code>true_statement</code> is executed if <code>condition</code> evaluates to <code>true</code>. |
− | false_statement is executed if condition evaluates to false. | + | <code>false_statement</code> is executed if <code>condition</code> evaluates to <code>false</code>. |
− | + | A compile-time error occurs if the type of <code>condition</code> does not evaluate to a <code>boolean</code> value. | |
− | === | + | === multiple statements in <code>if then</code> branch === |
− | If you need two or more statements for true_statement or false_statement, | + | If you need two or more statements for <code>true_statement</code> or <code>false_statement<code>, enclose them within a <code>[[Begin|begin]] … [[End|end]]</code> [[Block]] (compound statement). |
<syntaxhighlight> | <syntaxhighlight> | ||
− | + | if boolean_condition then | |
− | + | begin | |
− | + | statement_zero; | |
− | + | statement_one; | |
− | + | statement_two; | |
− | + | end; | |
</syntaxhighlight> | </syntaxhighlight> | ||
− | == | + | |
− | + | == external references == | |
+ | |||
+ | * official documentation: [https://www.freepascal.org/docs-html/ref/refsu57.html Reference guide: § “The <code>If..then..else</code> statement”] | ||
{{Keywords}} | {{Keywords}} | ||
[[Category:Pascal]] | [[Category:Pascal]] | ||
[[Category:Control Structures]] | [[Category:Control Structures]] |
Revision as of 01:26, 24 January 2018
│
English (en) │
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;
external references
- official documentation: Reference guide: § “The
If..then..else
statement”
Keywords: begin — do — else — end — for — if — repeat — then — until — while