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Top Forums UNIX for Beginners Questions & Answers Replace substring by longest string in common field (awk) Post 303042961 by beca123456 on Tuesday 14th of January 2020 06:55:59 AM
Old 01-14-2020
Brilliant !

However, although I think I understand the following lines, I cannot place them in the context:
Code:
# When reading the input file for the first time, create an array based on $1 for which the values are $3 if length($3)>a[$1] or b[$1] if not.
# How come this line does not trigger an error since a[$1] is not yet defined?
b[$1]=length($3)>a[$1]?$3:b[$1]

# Defining a[$1]
# if length($3) > a[$1], then a[$1] equals length($3), otherwise equals a[$1]
a[$1]=length($3)>a[$1]?length($3):a[$1]

 

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FGETS(3)								 1								  FGETS(3)

fgets - Gets line from file pointer

SYNOPSIS
string fgets (resource $handle, [int $length]) DESCRIPTION
Gets a line from file pointer. PARAMETERS
o $handle -The file pointer must be valid, and must point to a file successfully opened by fopen(3) or fsockopen(3) (and not yet closed by fclose(3)). o $length - Reading ends when $length - 1 bytes have been read, or a newline (which is included in the return value), or an EOF (whichever comes first). If no length is specified, it will keep reading from the stream until it reaches the end of the line. Note Until PHP 4.3.0, omitting it would assume 1024 as the line length. If the majority of the lines in the file are all larger than 8KB, it is more resource efficient for your script to specify the maximum line length. RETURN VALUES
Returns a string of up to $length - 1 bytes read from the file pointed to by $handle. If there is no more data to read in the file pointer, then FALSE is returned. If an error occurs, FALSE is returned. CHANGELOG
+--------+-----------------------------+ |Version | | | | | | | Description | | | | +--------+-----------------------------+ | 4.3.0 | | | | | | | fgets(3) is now binary safe | | | | +--------+-----------------------------+ EXAMPLES
Example #1 Reading a file line by line <?php $handle = @fopen("/tmp/inputfile.txt", "r"); if ($handle) { while (($buffer = fgets($handle, 4096)) !== false) { echo $buffer; } if (!feof($handle)) { echo "Error: unexpected fgets() fail "; } fclose($handle); } ?> NOTES
Note If PHP is not properly recognizing the line endings when reading files either on or created by a Macintosh computer, enabling the auto_detect_line_endings run-time configuration option may help resolve the problem. Note People used to the 'C' semantics of fgets(3) should note the difference in how EOF is returned. SEE ALSO
fgetss(3), fread(3), fgetc(3), stream_get_line(3), fopen(3), popen(3), fsockopen(3), stream_set_timeout(3). PHP Documentation Group FGETS(3)
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