reg exp

[superstarjpmc]

I have a string as below.

"o=this_is_p1,o=value"

I want to extract the value : 'this_is_p1' using a REG_EXP.

Can anyone help ?
regs
david j

 

[TrojanWarBlade]

print "$1\n" if /^([^,]+),/;

Or you could split on comma.




(very injured) Trojan.

 

[tchatzi]

$str = "o=this_is_p1,o=value";
$str =~ /=(.*),/;

print $1;

this will print: [blue]this_is_p1[/blue]


``The wise man doesn't give the right answers,
he poses the right questions.''
TIMTOWTDI

 

[duncdude]

Hi David

Bit safer to go about this Trojan's way

i.e.

^ (caret) to force the regex to look from the start of the line
no use of .* - which could copy more than you require should you need to use this for longer strings with more commas in

Trojan's example is forcing the regex to start at the beginning of the line - which is what you require - then finding any non-comma characters. I guess this is exactly what you need


Kind Regards
Duncan

 

[tchatzi]

If you want it safe this is the way. Considering that the value you are searching for, might be somewhere in the middle.

$str = "a=this_is_p1,a=value1,b=this_is_p2,b=value2,o=this_is_p3,o=value3";
@str=split(/,/,$str);
foreach $i (@str){
  ($key, $value) = split(/=/, $i);
  if (exists $pairs{$key}){
    $key.="v";
  }
  $pairs{$key}=$value;
}
foreach $key(sort keys %pairs){
  print "$key:  $pairs{$key}\n";
}

This last print will give you this

a:  this_is_p1
av: value1
b:  this_is_p2
bv: value2
o:  this_is_p3
ov: value3

or if you want, lets say, the [blue]value2[/blue]
just

print $pairs{bv};

or if you want [blue]this_is_p3[/blue]
just

print $pairs{o};

``The wise man doesn't give the right answers,
he poses the right questions.''
TIMTOWTDI

 

[stevexff]

"o=this_is_p1,o=value"

This looks like the query string part of a URL. If that is the case, use CGI.