Foreachkey

• key_variable is the current key (or index). The internal container cursor is moved to point at the next key-value pair (or indexed item).
• The type of key_variable doesn't matter.
• loop_increment is executed at the end of each iteration. It is optional.

• Source code(UnigineScript)

  int map[] = ( "begin" : "flower", "middle" : "fruit", "end" : "tree" );
  foreachkey(int i; map) {
  	log.message("%s\t=>\t%s\n",i,map[i]);
  }

  The result is:
  Output

  begin   =>      flower
  end     =>      tree
  middle  =>      fruit

• Source code(UnigineScript)

  int map[] = ( "begin" : "flower", "middle" : "fruit", "end" : "tree" );
  foreachkey(int i, j = 0; map; j++) {
  	log.message("%d: %s\t=>\t%s\n",j,i,map[i]);
  }

  The result is:
  Output

  0: begin   =>      flower
  1: end     =>      tree
  2: middle  =>      fruit

Modifications of keys inside the foreachkey block do not affect the map, however, values can be modified directly.

int map[] = ( "begin" : "flower", "middle" : "fruit", "end" : "tree" );
foreachkey(int i; map) {
	i = "first";	// it doesn't affect the map
	map[i] = -9.6;	// it's ok, map is changed
}

In case foreachkey structure is called within another foreachkey structure, for each block a copy of the map should be stored. (Such approach allows for higher performance.)

int map[] = ( "1" : "head", "2" : "foot" );

int copy[];
copy.copy(map);

foreachkey(int i; map) {
	foreachkey(int j; copy)	// foreachkey(int j; map) will generate an error
	{
		log.message("%s\t->\t%s\t%s\t->\t%s\n",i,map[i],j,map[j]);
	}
}

1	->	head	1	->	head
1	->	head    2	->	foot
2	->	foot	1	->	head
2	->	foot	2	->	foot