Processing Variable Length Text Fields (PHP Cookbook)

18.13. Processing Variable Length Text Fields

18.13.1. Problem

You want to read delimited text fields from a file. You might, for example, have a database program that prints records one per line, with tabs between each field in the record, and you want to parse this data into an array.

18.13.2. Solution

Read in each line and then split the fields based on their delimiter:

$delim = '|';

$fh = fopen('books.txt','r') or die("can't open: $php_errormsg");
while (! feof($fh)) {
    $s = rtrim(fgets($fh,1024));
    $fields = explode($delim,$s);
    // ... do something with the data ... 
}
fclose($fh) or die("can't close: $php_errormsg");

18.13.3. Discussion

To parse the following data in books.txt:

Elmer Gantry|Sinclair Lewis|1927
The Scarlatti Inheritance|Robert Ludlum|1971
The Parsifal Mosaic|Robert Ludlum|1982
Sophie's Choice|William Styron|1979

Process each record like this:

$fh = fopen('books.txt','r') or die("can't open: $php_errormsg");
while (! feof($fh)) {
    $s = rtrim(fgets($fh,1024));
    list($title,$author,$publication_year) = explode('|',$s);
    // ... do something with the data ... 
}
fclose($fh) or die("can't close: $php_errormsg");

The line length argument to fgets( ) needs to be at least as long as the longest record, so that a record doesn't get truncated.

Calling rtrim( ) is necessary because fgets( ) includes the trailing whitespace in the line it reads. Without rtrim( ), each $publication_year would have a newline at its end.

18.13.4. See Also

Section 1.12 discusses ways to break apart strings into pieces; Section 1.10 and Section 1.11 cover parsing comma-separated and fixed-width data; documentation on explode( ) at http://www.php.net/explode and rtrim( ) at http://www.php.net/rtrim.