从大文本文件（长度可变的文本）中读取选定的内容

Question

I'm looking to read contents of a file between two tags in a large text file (so can't read the whole file at once due to memory restrictions on my server provider). This file has around 500000 lines of text.

This ( PHP: Read Specific Line From File ) isn't an option (I don't think), as the text I need to read varies in length and will take up multiple lines (varies from 20-5000 lines).

I am planning to use fopen , fread (read only) and fclose to read the file contents. I have experience of using these functions already.

I am looking to read all the contents in a selected part of the file. ie

File contents example

    <<TAGNAME-1>>AAAA AAAA AAAA<<//TAGNAME-1>>
    <<TAGNAME-2>>TEXT TEXT TEXT<<//TAGNAME-2>>

To select the text "AAAA AAAA AAAA" between the <<TAGNAME-1>> and <<//TAGNAME-1>> when TAGNAME-1 is called as a variable in my script.

How could I go about selecting all the text between the two tags that I require? (and ignore the remainder of the file) I have the ability to create the two tags where required in my php script - my issue is implementing this within the fread function.

Answer 1

You could grep the text file which would only return the text with a matching tag.

 $tagnum = 2;     //variable 
 $pattern = "<<TAGNAME-";   
 $searchstr = $pattern.$tagnum;   //concat the prefix with the tag number
 $fpath ="testtext.txt";  //define path to text file
 $result = exec('grep -in "'.$searchstr.'" '.$fpath);
 echo $result;

Where $tagnum would define each tag to search. I've tested it in my sandbox and it works as expected. Note this will read the whole line until the end tad or newline is reached. Regards,