Laine at 17:05, 11 June 2007

Laine — Mon, 11 Jun 2007 17:05:40 GMT

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==Synopsis==

*foreach (<var> : <expr>) <statement>;
*foreach (<var>, <var2>, ... ,<varN> : <expr>) <statement>;

/* MudOS compatibility only - not for new code: */
foreach (<var> in <expr>) <statement>;
foreach (<var>, <var2>, ... ,<varN> in <expr>) <statement>;

==Description==

<expr> is evaluated and has to yield an array, a string or a mapping.
The values of <expr> (in case of the string, the integer values
of the characters) are then assigned one after another to <var>
and <statement> is execute for every assignment.

If <expr> is a mapping, the keys are assigned to <var>, and
the values for each key are assigned in order to <var2>..<varN>.
If there are more values than variable, the extraneous values
are ignored.

If there are more variables than necessary, the unneeded ones
are not changed.

Every <var> specification can declare a new local variable, whose
scope is the whole foreach() statement.

A 'break' in the 'statement' will terminate the loop. A
'continue' will continue the execution from the beginning of
the loop.

WHAT HAPPENS IF <expr> IS CHANGED IN THE LOOP?

If <expr> yields an array:
* assignments to single array elements or to array ranges effect
the values assigned to the variable:
a = ({1, 2, 3})
foreach(x : a) { a[1..2] = ({4, 5}); write(x+" "); }
will write ("1 4 5 ").
* operations which implicitely copy the array (this includes
range assignments which change the size) don't have an effect
on the loop.

If <expr> yields an mapping, the loop will run over the indices
the mapping had at the begin of the loop. Deleted indices are silently
skipped, new indices ignored, but changes of the data of existing
indices are acknowledged.

If <expr> yields a string, it can't be changed anyway.

==Warning==

The additional syntax forms using "in" as keyword are meant
to make re-engineering of MudOS objects easier. Do not use them
for newly written code, as they may not be available in future.

==Examples==

// Call quit() in all interactive users
foreach(o : users()) o->quit();
foreach(object o : users()) o->quit();

// Print the contents of a mapping <m>
foreach(key, value : m) printf("%O:%O\n", key, value);
foreach(mixed key, mixed value : m) printf("%O:%O\n", key, value);

==See Also==

[[man for|for(LPC)]]

Man foreach - Revision history

Laine at 17:05, 11 June 2007