Regex Incorrect parameters

Psymon

Hi All

Thanks in advance for any assistance. I understand there are a multitude of regex questions and answers out there but i can seem to nail this one....

I am attempting to parse log file data, everything appeared to be working ok until comparing the result sets with the original logs.

I have the following log structure:

07/11 22:49:36:808: Item_Process_Start
07/11 22:49:36:808: LogData
...LogData
...LogData
...LogData
...LogData
07/11 22:49:46:990: Item_Process_End_Success

07/11 22:49:36:808: Item_Process_Start
07/11 22:49:36:808: LogData
...LogData
...LogData
...LogData
...LogData
07/11 22:49:46:990: Item_Process_End_Failed

07/11 22:49:36:808: LogData
...LogData
...LogData
...LogData
...LogData
07/11 22:49:46:990: Item_Process_End_Success

I am trying to capture log data for items between Item_Process_Start and Item_Process_End_Success i do not want to include the failed items data as it is for generating a report of successful items only.

My regex (quite bloated) is as follows:

(?\d{1,2}:)/(?\d{1,2}:)[\s](?\d{1,2}:)(?\d{1,2}:)(?\d{1,2}:)(?\d{3}:)\sItem_Process_Start(?s:.*?.*)(?\d{1,2}:)/(?\d{1,2}:)[\s](?\d{1,2}:)(?\d{1,2}:)(?\d{1,2}:)(?\d{3}:)\sItem_Process_End_Success

It seems this is a rather greedy search and will also capture failed all items?

Any help on how i can capture the successful items only would be great.

Many thanks

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
If you don't need to do this using regular expressions, then I'd use ordinary string parsing which should be quicker and less error prone for complex multi-line stuff such as this.

The following worked fine on the file as you've posted it though I wasn't sure whether the absence of an 'Item_Process_Start' line in the final item was an error or not:

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;

class Test
{
static void Main()
{
string[] lines = File.ReadAllLines("psymon.txt");
List successes = new List();
List logData = null;

for(int i = 0; i < lines.Length; i++)
{
lines[i] = lines[i].Trim();
if (lines[i] == "") continue;

if(lines[i].EndsWith("Item_Process_Start"))
{
logData = new List();
logData.Add(lines[i]);
}
else if(lines[i].EndsWith("Item_Process_End_Failed"))
{
logData = new List();
}
else if(lines[i].EndsWith("Item_Process_End_Success"))
{
logData.Add(lines[i]);
successes.Add(String.Join("\r\n", logData.ToArray()));
}
else
{
logData.Add(lines[i]);
}
}

// check it worked
foreach(string success in successes) Console.WriteLine("{0}\n", success);
Console.ReadKey();
}
}
Psymon14y ago
Thats great stuff .

I will check / test this today and see how this performs.

Rather good timing i was just coming on the site to post an update as it seems the following also cured my issue (in part 99%)

var rxBlock = new Regex(rxStripBlock,RegexOptions.RightToLeft | RegexOptions.Singleline);

I never considered righttoleft option in regex :)

However you are right for a large file this is a little slow so i will incorporate your method and benchmark them to see which performs.

That said i can see your method has much more control over how the parameters of the log file are handled and would allow better parsing

Thanks Vulpes your a star