Greetings,

I am in need of guidance. I am attempting to capture elements from a string which may or may not exist.

Two possible (overly simplistic) strings are below, and I need to capture a, b and c (if they exist).

my $input1 = 'a=1 gibberish b=2 c=3';
my $input2 = 'a=1 gibberish c=3';

[download]

I threw this together with a conditional (?) on the b element. I don't get the results I expected, which probably means my expectations are wrong. Any way to get what I want with just a single pass? 

my $input1 = 'a=1 gibberish b=2 c=3';
my $input2 = 'a=1 gibberish c=3';

# normal capture
my $match1 =  '^(?<a>a=(\d)).*?(?<b>b=(\d)).*?(?<c>c=(\d))$';
# conditional capture
my $match2 =  '^(?<a>a=(\d)).*?(?<b>b=(\d))?.*?(?<c>c=(\d))$';

# using $match1

print "\n\nUsing match1 ---> $match1\n\n";
if ($input1 =~ m/$match1/){ print "Input1: a is $+{a} and b is $+{b} a
+nd c is $+{c}\n"; }
else { print "Input1: didn't match\n"; }

if ($input2 =~ m/$match1/){ print "Input2: a is $+{a} and b is $+{b} a
+nd c is $+{c}\n"; }
else { print "Input2: didn't match\n"; }

# using $match2 
# conditional capture on the b element
print "\n\nUsing match2 ---> $match2\n\n";

if ($input1 =~ m/$match2/){ print "Input1: a is $+{a} and b is $+{b} a
+nd c is $+{c}\n"; }
else { print "Input1: didn't match\n"; }

if ($input2 =~ m/$match2/){ print "Input2: a is $+{a} and b is $+{b} a
+nd c is $+{c}\n"; }
else { print "Input2: didn't match\n"; }

[download]

Output : 

Using match1 ---> ^(?<a>a=(\d)).*?(?<b>b=(\d)).*?(?<c>c=(\d))$

Input1: a is a=1 and b is b=2 and c is c=3
Input2: didn't match


Using match2 ---> ^(?<a>a=(\d)).*?(?<b>b=(\d))?.*?(?<c>c=(\d))$

Input1: a is a=1 and b is  and c is c=3
Input2: a is a=1 and b is  and c is c=3

[download]

Thanks,
Tobin

In reply to regular expression help by Tobin Cataldo

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