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How do I print a partial array?

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Contributed by shampoo7 on Jun 13, 2001 at 21:38 UTC
Q&A  > arrays


Description:

I am trying to print an array. But not all the elements are intialize. i.e.
@b[0]=c; @b[1]=undef; @b[3]=undef; @b[4]=a;
so when i use print "@b", I want only @b[0] and @b[4] to be printed. How do I skip the undef elements?

Edited 2001/06/13 by Ovid

Answer: How do I print a partial array?
contributed by MeowChow

grep anyone?

print grep defined $_, @b;
Answer: How do I print a partial array?
contributed by Albannach

You can test whether an element has been defined with the sensibly named defined function, so one way might be something like:

for my $element (@a) { print $element if defined($element); }
Answer: How do I print a partial array?
contributed by Sifmole

print map { defined $_ ? $_ : ''; } @b; would be one way.

Answer: How do I print a partial array?
contributed by dragonchild

If you already know what elements you want to print, then doing something like print @b[0,4,6..8], "\n"; will print just those elements. This is called an array slice.

Answer: How do I print a partial array?
contributed by Bloodelf

Another way....

foreach ( @b ) { print "$_\n" if defined $_; }

Edited by davido: Added "defined" to conditional so that elements containing '0' would still print, while undefined elements are skipped.

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