Difference between revisions of "Loops"
(→Manipulating a loop: Removed note on Fenix 0.85 and below behaviour.)
Latest revision as of 20:57, 21 July 2009
LOOP-END, WHILE-END, REPEAT-UNTIL, FOR-END, FROM-END
Loops are used to create iterations in your code. The statements between these words will get repeated depending on a condition. There are several types of loops:
Loop ... End
Loop // Statements End
- The statements will be repeated indefinitely.
While ... End
While(<condition>) // Statements End
- The statements will be repeated while condition is fulfilled.
Repeat ... Until
Repeat // Statements Until(<condition>)
- The statements will be repeated until condition is fulfilled.
For ... End
For( [ <initializer> ] ; [ <condition> ] ; [ <counting expression> ] ) // Statements End
- First, initializer will be executed. Then the statements will be repeated until condition is fulfilled. After each run of the statements, counting expression is executed.
From ... End
From <variable>=<startvalue> To <endvalue> [ Step <incrementvalue> ] ; // Statements End
- First, startvalue will be assigned to the variable. Then the statements will be repeated and incrementvalue added to the variable. When the variable is greater than endvalue, the loop ends.
- Note that incrementvalue must be a constant. The
Step <incrementvalue>part is optional.
Manipulating a loop
There are more ways to manipulate a loop, both internally and externally.
If the code inside a loop reaches a break; statement, the loop is immediately ended. This is particularly useful in the Loop-End loop, because that one has no other way to end the loop and continue code beneath it.
If the code inside a loop reaches a continue; statement, it executes the possible count- or stepping statement and then continues to the checking of the condition. So in a Repeat-Until loop, it would just skip to the Until() part.
import "mod_say" Const startvalue = 1; endvalue = 8; incrementvalue = 2; End Process Main() Private int c; Begin /* Loop */ c = startvalue; Loop say("Loop: " + c); c+=incrementvalue; if(c>endvalue) break; end End say("End Loop: " + c); /* While */ c = startvalue; While(c<=endvalue) say("While: " + c); c+=incrementvalue; End say("End While: " + c); /* Repeat */ c = startvalue; Repeat say("Repeat: " + c); c+=incrementvalue; Until(c>endvalue) say("End Repeat: " + c); /* For */ For(c=startvalue;c<=endvalue;c+=incrementvalue) say("For: " + c); End say("End For: " + c); /* From */ From c=startvalue To endvalue Step incrementvalue; say("From: " + c); End say("End From: " + c); End
In the example, all the loops do the same thing, illustrated by the use of the same constants. The output is:
Loop: 1 Loop: 3 Loop: 5 Loop: 7 End Loop: 9 While: 1 While: 3 While: 5 While: 7 End While: 9 Repeat: 1 Repeat: 3 Repeat: 5 Repeat: 7 End Repeat: 9 For: 1 For: 3 For: 5 For: 7 End For: 9 From: 1 From: 3 From: 5 From: 7 End From: 9