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How can I add all the numbers in an array with out doing a foreach loop?

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Contributed by draco_iii on Jun 09, 2000 at 20:14 UTC
Q&A  > arrays


Description:

That is, I want to avoid having to write any kind of explicit loop, such as:
my $sum = 0; for ( @numbers ) { $sum += $_; }
I'd rather do it in a single statement. Of course, I could wrap the above in a sub, but are there any better ways?

Answer: How can I add all the numbers in an array with out doing a foreach loop?
contributed by chromatic

Using eval, which of course has inherent dangers:

@e = (1,2,3,4); $sum = eval join '+', @e;
Answer: How can I add all the numbers in an array with out doing a foreach loop?
contributed by brother ab

In functional style, using reduce from List::Util:

@a = (1..10); use List::Util qw(reduce); $sum = reduce { $a + $b } @a;
Answer: How can I add all the numbers in an array with out doing a foreach loop?
contributed by myuserid7

List::Util provides a sum() function:

use List::Util qw(sum); $sum = sum(1..10);
Answer: How can I add all the numbers in an array with out doing a foreach loop?
contributed by I0

For a positive sum:

unpack "%123d*" , pack( "d*", @numbers);

For a signed long:

unpack "l", pack( "l", unpack( "%32d*", pack( "d*", @numbers)));
Answer: How can I add all the numbers in an array with out doing a foreach loop?
contributed by DStaal

Just to have the one-line loop on here, since your real complaint is to get it all on one line:

(Note that you'd have to declare $sum someplace before the loop yet.)

@a = (1..10); $sum += $_ for @a;
Answer: How can I add all the numbers in an array with out doing a foreach loop?
contributed by aaron_baugher

Surprised no one's added the Lisp-style recursive solution yet:

sub radd { return( defined $_[0] ? $_[0] + radd(@_[1..$#_]) : 0 ); } my $sum = radd(1..10);
Answer: How can I add all the numbers in an array with out doing a foreach loop?
contributed by lkench

Someone might be interested in:

my $sum = [map {$sum +=$_} @arrayToSum]->[$#arrayToSum];
I found it useful anyway.

--lkench

Answer: How can I add all the numbers in an array with out doing a foreach loop?
contributed by smithfarm

Use the grep function:

my $sum; grep { $sum += $_ } @arrayToSum;
Or, equivalently, use the map function:
my $sum; map { $sum += $_ } @arrayToSum;
Both grep and map apply the code in the code block to each element of @arrayToSum. The _result_ of the grep/map function is not interesting to us in this case, so we ignore it.

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