5.3 If Statements
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An if_statement selects for execution at most one of the enclosed sequences_of_statements, depending on the (truth) value of one or more corresponding conditions.
Syntax
if_statement ::= if condition then sequence_of_statements {elsif condition then sequence_of_statements} [else sequence_of_statements] end if;
condition ::= boolean_expression
Name Resolution Rules
A condition is expected to be of any boolean type.
Dynamic Semantics
For the execution of an if_statement, the condition specified after if, and any conditions specified after elsif, are evaluated in succession (treating a final else as elsif True then), until one evaluates to True or all conditions are evaluated and yield False. If a condition evaluates to True, then the corresponding sequence_of_statements is executed; otherwise none of them is executed.
Examples
Examples of if statements:
if Month = December and Day = 31 then
Month := January;
Day := 1;
Year := Year + 1;
end if;
if Line_Too_Short then
raise Layout_Error;
elsif Line_Full then
New_Line;
Put(Item);
else
Put(Item);
end if;
if My_Car.Owner.Vehicle /= My_Car then -- see 3.10.1
Report ("Incorrect data");
end if;
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