Re: getting a number out of a string....


David Gilden wrote:
> Greetings,
>
> How does one just get the number part out of a string?
>
> The script below just prints 1.
>
> #!/usr/bin/perl
>
> @str = ('Gambia001.tiff','Gambia0021.tiff','Gambia031.tiff','Gambia035.tiff') ;
>
> foreach $str (@str) {
> $num = ($str =~ /\d+/);

You are running a pattern match in a scalar context. In a scalar
context, the mattern match simply returns 1 or "" (true or false)
depending on whether or not the pattern match succeeded.

You have several options:
(1)Capture what you want to match, and refer to it later:
if ($str =~ /(\d+)/){
$num = $1;
# . . .
}
(2) Call the pattern match in list context, matching globally:
($num) = ($str =~ /\d+/g);
(3) Call the pattern match in list context, and capture what you want
to match:
($num) = ($str =~ /(\d+)/);

This is all explained in detail in:
perldoc perlop
perldoc perlretut
perldoc perlre
perldoc perlreref

Paul Lalli

.

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