The book Im learning perl from has very little information
on the special variable $_ all it basically says is that
if <STDIN> isnt assigned to a variable its assigned to $_
and it can be used with a foreach loop
I've search some on the web but most of the tutorials I've
run across have relativley little information on $_,
although i've learned a bit more on it.
one of the things I found out was that it works with a while loop, so I tried a few different ways of using it.
but i cant figure out why it doesnt work for the second one and why the third one seems to be off by one every time it prints
print "first\n";
while (<STDIN>)
{
print;
print "***\n";
last if(eof);
}
print "second\n";
while (<STDIN>!=eof)
{
print;
print "***\n";
}
print "\nthird\n";
while ((chomp($tst=<STDIN>))!=eof)
{print $tst ;
print "***\n";
}
I'm runing this on a windoze system.
the first while statement works as I expect it to,basically
you type something hit return it prints what you typed when
you hit ctrl-z it exits.
the second one doesnt work, if you hit enter twice it exits out of the loop, from what I can guess is that $_ isn't being assigned, but no idea why it wont do the comparison
.
The third one works buts its a lil off, after the second
entry it prints stuff.
from what I understand all 3 should produce the same output
if someone could help me out and set me straight as to
why the outputs are different I would greatly appreciate it
-
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.
|
