When you do this:
map { whatever } @array;
you are taking the initial contents of the array as a list (that is, making a list based on the initial array contents), and map iterates over that list. If anything happens within the map block to change the number of array elements (adding or removing), this has no effect whatsoever on the initial list that drives the map iterations. Consider:
perl -le '@a=qw/a a/; map{push @a,"A"; print "@a"} @a'
# prints:
a a A
a a A A
perl -le '@a=qw/a a/; map{@a=(); print "@a"} @a'
# prints two blank lines
But when you do this:
foreach (@array) {
# add or remove elements in @array...
}
you are asking for trouble. Some variations on that theme might "work" (though maybe not in the manner you intended), but in general it's a bad practice.
Don't use "for" to iterate over an array if you plan on adding or removing array elements within the loop. Use "while" for that (and be really attentive about making sure you provide the right exit condition(s) to get out of the loop).
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|