Hello blaui,

You can just use a regex:

use strict;
use warnings;

for my $string ("BCInletTemperature = 90[C]", "BCInletTemperature = 33
+.56[C]")
{
    print "$1\n" if $string =~ / = \s* ([0-9.]+) \[ /x;
}
[download]

Output:

16:59 >perl 1906_SoPW.pl
90
33.56

17:03 >
[download]

The regex says: match an equals sign, followed by zero or more whitespace characters, followed by one or more digit-or-decimal-point characters, followed by a left square bracket; and capture the string of digit-or-decimal-point characters in $1. The /x modifier on the regex means to not match whitespace inside the regex: this just makes the regex easier to read.

Update: Note that it is necessary to escape the square bracket to tell the regex engine that this is a character to be matched literally, and not the beginning of a character class.

Hope that helps,