The ++ is after variable, so it increments after you test it; however, the print is a separate statement. If you used Compound Statements instead of Statement Modifiers, your code would better reflect the actual flow and would look like: 
$i=0;
if ($i++) {
    print 'first=' , $i, ', ';
}
if ($i++) {
    print 'middle=' , $i, ', ';
}
if ($i++) {
    print 'last=' , $i, ', ';
}
if ($i++) {
    print 'beyond=' , $i, ', ';
}

[download]
For what you want, you probably mean: 
$i=0;
if ($i++) {
    print 'first=' , $i - 1, ', ';
}
if ($i++) {
    print 'middle=' , $i - 1, ', ';
}
if ($i++) {
    print 'last=' , $i - 1, ', ';
}
if ($i++) {
    print 'beyond=' , $i - 1, ', ';
}

[download]
which is admittedly a little awkward. More natural would be to post-increment after your print, except you clearly intend the incrementation to happen independently of whether the print happens. Perhaps 
$i=0;
print 'first=' , $i, ', ' if $i;
$i++;
print 'middle=', $i, ', ' if $i;
$i++;
print 'last='  , $i, ', ' if $i;
$i++;
print 'beyond=', $i if $i;
$i++;

[download]
or 
my $i=0;
outputter('first', $i++);
outputter('middle', $i++);
outputter('last', $i++);
outputter('beyond', $i++);

sub outputter {
    my ($txt, $i) = @_;
    print "$txt=$i, " if $i;
}

[download]

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In reply to Re: Auto-increment behaviour, is this normal and why? by kennethk
in thread Auto-increment behaviour, is this normal and why? by Gilles Maisonneuve

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