Control Structures: Difference between revisions

From Kolmafia
Jump to navigation Jump to search
imported>Aqualectrix
added a section on break/continue, mostly to note that they exist
imported>Aqualectrix
added switch statement syntax, ripped from r7098 and r7100 commit logs
Line 11: Line 11:


{}
{}
== switch ==
  switch (value)
  {
    case expression:
      statement
      statement
      ...
      break;
    default:
      statement
      statement
      ...
      break;
  }


== while ==
== while ==
Line 60: Line 75:
See http://kolmafia.sourceforge.net/advanced.html#maps for more details on maps.
See http://kolmafia.sourceforge.net/advanced.html#maps for more details on maps.
== continue/break ==
== continue/break ==
Like many languages with looping structures, ASH supports the break and continue statements.  All looping structures (for, while, repeat until, and foreach) support these statments.
Like many languages with looping structures, ASH supports the break and continue statements.  All looping structures (for, while, repeat until, and foreach) support these statements.


   break;
   break;
Breaks out of the smallest enclosing loop.
Breaks out of the smallest enclosing loop.  In a switch statement, breaks out of the switch statement.  Execution resumes at the first statement after the end of the loop/switch statement.


   continue;
   continue;
Continues on to the next iteration of the loop (skipping any statments in this iteration that occur after the continue; statement).
Continues on to the next iteration of the loop (skipping any statments in this iteration that occur after the continue statement).  In a switch statement, continue is allowed iff the switch is inside a loop, and acts as any other continue.

Revision as of 05:39, 18 November 2009

if/else

if (boolean)

{}

else if (boolean)

{}

else

{}

switch

 switch (value) 
 {
   case expression:
     statement
     statement
     ...
     break;
   default:
     statement
     statement
     ...
     break; 
 }

while

while (boolean)

{}

repeat until

repeat {} until (boolean);

for

for x from a to b by c

is the general case. You don't need to specify whether it's going up or down - although doing so by using upto or downto does allow a runtime check to make sure you didn't screw up.

If you don't specify "c", it defaults to incrementing/decrementing by 1. The first iteration is at a and the last is at b (that is to say, it goes from a to b, inclusive).

foreach

foreach x in map

{}

"map" must be an aggregate - a map or a slice. x takes on each value of the map index in turn. If there is more than one index, x iterates over the first index.

For example:

 boolean [int][string] map;
 map[15]["test"] = true;
 foreach int_index in map
 {
   print(int_index); //this will print '15' once, since there is only one valid value for this index
   foreach string_index in map[int_index] //this iterates over the "slice" of the map where 1 is fixed as the index
   { 
     print(string_index); //This will print "test" once, since there is only one valid value for this index
     print(map[int_index][string_index]); //this will print "true"
   }
 }

So the output is

 15
 test
 true

Note that instead of nesting foreach statements, for a multidimensional map, two iterators can be used inline.

 foreach x,y in map

is identical to

 foreach x in map
 {
   foreach y in map[x]
 }

See http://kolmafia.sourceforge.net/advanced.html#maps for more details on maps.

continue/break

Like many languages with looping structures, ASH supports the break and continue statements. All looping structures (for, while, repeat until, and foreach) support these statements.

 break;

Breaks out of the smallest enclosing loop. In a switch statement, breaks out of the switch statement. Execution resumes at the first statement after the end of the loop/switch statement.

 continue;

Continues on to the next iteration of the loop (skipping any statments in this iteration that occur after the continue statement). In a switch statement, continue is allowed iff the switch is inside a loop, and acts as any other continue.