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Asked: 2026-05-11T00:41:49+00:00

I’m probably doing this all wrong. I have a text file full of data

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I’m probably doing this all wrong. I have a text file full of data and I want to match and replace patterns of ‘item’ and ‘catalog number’ that are in the file. But the order of each element in the file is very important, so I want to match/replace starting from the top of the file and then work my way down.

The code snippet below actually works, but when I execute it, it replaces the third instance of the ‘SeaMonkey’ & ‘SMKY-1978’ pattern and then it replaces the second instance of that pattern. What I’d like it to do is replace the first instance of the pattern and then the second.

So I’d like the output to say ‘Found Kurt’s SMKY-1978 SeaMonkeys’ and then ‘Found Shane’s SMKY-1978 SeaMonkeys’ and then leave Mick’s SMKY-1978 SeaMonkeys alone since I only want to find and replace the first 2 instances of the pattern. Right now it says ‘Found Shane’s SMKY-1978 SeaMonkeys’ and ‘Found Mick’s SMKY-1978 SeaMonkeys’ because it is matching the last pattern each time the for loop is executed.

So am I missing a subtle little known regex character or am I just doing what I want to do completely and utterly wrong?

Here is the working code:

# my regexp matches from the bottom to the top but I'd like it to replace from the top down local $/=undef; my $DataToParse = <DATA>; my $item = 'SeaMonkeys'; my $catNum = 'SMKY-1978'; my $maxInstancesToReplace = 2; parseData(); exit();  sub parseData {     for (my $counter = 0; $counter < $maxInstancesToReplace; $counter++) {         # Stick in a temporary text placeholder that I will replace later after more processing         $DataToParse =~ s/(.+)\sELEMENT\s(.+?)\s\(Item := \'$item\'.+?CatalogNumber := \'$catNum.+?END_ELEMENT(.+)/$1 ***** Found $2\'s $catNum $item. (counter: $counter) *****$3/s;     }      print('Here's the result:\n$DataToParse\n'); }  __DATA__     ELEMENT Kurt (Item := 'BrightLite',                   ItemID := 29,                   CatalogNumber := 'BTLT-9274',                   Vendor := 100,     END_ELEMENT      ELEMENT Mick (Item := 'PetRock',                   ItemID := 36,                   CatalogNumber := 'PTRK-3475/A',                   Vendor := 82,     END_ELEMENT      ELEMENT Kurt (Item := 'SeaMonkeys',                   ItemID := 12,                   CatalogNumber := 'SMKY-1978/E',                   Vendor := 77,     END_ELEMENT      ELEMENT Joe (Item := 'Pong',                  ItemID := 24,                  CatalogNumber := 'PONG-1482',                  Vendor := 5,     END_ELEMENT      ELEMENT Shane (Item := 'SeaMonkeys',                    ItemID := 1032,                    CatalogNumber := 'SMKY-1978/E',                    Vendor := 77,     END_ELEMENT      ELEMENT Kurt (Item := 'Battleship',                   ItemID := 99,                   CatalogNumber := 'BTLS-5234',                   Vendor := 529,     END_ELEMENT      ELEMENT Mick (Item := 'SeaMonkeys',                   ItemID := 8,                   CatalogNumber := 'SMKY-1978/F',                   Vendor := 77,     END_ELEMENT      ELEMENT Frank (Item := 'PetRock',                    ItemID := 42,                    CatalogNumber := 'PTRK-3475/B',                    Vendor := 82,     END_ELEMENT      ELEMENT Joe (Item := 'SeaMonkeys',                  ItemID := 8,                  CatalogNumber := 'SMKY-1979/A',                  Vendor := 77,     END_ELEMENT

And here is what it currently outputs:

Here's the result:         ELEMENT Kurt (Item := 'BrightLite',                       ItemID := 29,                       CatalogNumber := 'BTLT-9274',                       Vendor := 100,         END_ELEMENT          ELEMENT Mick (Item := 'PetRock',                       ItemID := 36,                       CatalogNumber := 'PTRK-3475/A',                       Vendor := 82,         END_ELEMENT          ELEMENT Kurt (Item := 'SeaMonkeys',                       ItemID := 12,                       CatalogNumber := 'SMKY-1978/E',                       Vendor := 77,         END_ELEMENT          ELEMENT Joe (Item := 'Pong',                      ItemID := 24,                      CatalogNumber := 'PONG-1482',                      Vendor := 5,         END_ELEMENT   ***** Found Shane's SMKY-1978 SeaMonkeys. (counter: 1) *****          ELEMENT Kurt (Item := 'Battleship',                       ItemID := 99,                       CatalogNumber := 'BTLS-5234',                       Vendor := 529,         END_ELEMENT   ***** Found Mick's SMKY-1978 SeaMonkeys. (counter: 0) *****          ELEMENT Frank (Item := 'PetRock',                        ItemID := 42,                        CatalogNumber := 'PTRK-3475/B',                        Vendor := 82,         END_ELEMENT          ELEMENT Joe (Item := 'SeaMonkeys',                      ItemID := 8,                      CatalogNumber := 'SMKY-1979/A',                      Vendor := 77,         END_ELEMENT
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1 Answer

  1. The best solution appears to be to grab each ELEMENT … END_ELEMENT section from the data and regex only one section at a time rather than feeding the whole complete data set to a regular expression at once. Not exactly what I was trying to accomplish, but I rewrote my program to do this piecemeal processing and it works like a charm.

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