SparForte - Reference - Flow of Control

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Flow of Control

The If Statement

if statements are used for conditional branching.

if x > y then
   put_line( "x is greater than y" );
elsif x = y then
   put_line( x is equal to y" );
else
   put_line( x is less than y" );
end if;

Example: The If Statement

The Case Statement

The case statement can test a variable for several different values.

type country is ( australia, u_k, brazil );
c : country;
...
case c is
when austraila =>
   put_line( "Australia" );
when u_k =>
   put_line( "United Kingdom" );
when brazil =>
   put_line( "Brazil" );
when others =>
   put_line( "Unexpected country" );
end case;

Example: The Case Statement

Multiple cases can be strung together using a vertical bar (|).

when brazil | u_k => -- brazil or U.K.

The "when" cases must not be variables (although constants are OK). The "when others" case is always required.

The While Loop Statement

The while loop is a pre-test loop. The commands in the loop are repeat while the condition is true and the condition is tested each time the first line of the loop is executed.

while x < y loop
x := @ + 1;
end loop;

Example: The While Statement

The For Loop Statement

The for loop increments its index variable by 1 until it iterates through the specified range. The index variable is automatically declared for you and only exists for the scope of the the loop. The range can either be numeric or enumerated.

for i in 1..10 loop
put( "i is " );
put_line( i );
end loop;

Example: The For Statement

To loop in reverse in a for loop, use "in reverse" instead of "in".