What's the difference between 'for' and 'foreach' in Perl?

Question

I see these used interchangeably. What's the difference?

Solution 1

There is no difference. From perldoc perlsyn:

The foreach keyword is actually a synonym for the for keyword, so you can use foreach for readability or for for brevity.

Solution 2

I see these used interchangeably.

There is no difference other than that of syntax.

Solution 3

Four letters.

They're functionally identical, just spelled differently.

Solution 4

Ever since its introduction in perl-2.0, foreach has been synonymous with for. It's a nod to the C shell's foreach command.

In my own code, in the rare case that I'm using a C-style for-loop, I write

for (my $i = 0; $i < $n; ++$i)

but for iterating over an array, I spell out

foreach my $x (@a)

I find that it reads better in my head that way.

Solution 5

From http://perldoc.perl.org/perlsyn.html#Foreach-Loops

The foreach keyword is actually a synonym for the for keyword, so you can use either. If VAR is omitted, $_ is set to each value.

# Perl's C-style
for (;;) {
    # do something
}

for my $j (@array) {
    print $j;
}

foreach my $j (@array) {
    print $j;
}

However:

If any part of LIST is an array, foreach will get very confused if you add or remove elements within the loop body, for example with splice. So don't do that.

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