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Top Forums Shell Programming and Scripting Understanding an example of perl map() function Post 303003544 by Corona688 on Friday 15th of September 2017 01:36:11 PM
Old 09-15-2017
map is confusing because it's actually a kind of loop. $1 is the bracketed part of /(.*)\// in this context.

The whole thing means, "For each item in @ARGV[N], do { /(.*)\//; output[N]=$1 }"

Then the whole thing is crammed into a "join" which returns them tab-separated.

I have no idea why it removes the ".trim", the .*\/ is a regex meaning "several of any character, followed by a forward slash". It just stops at the last forward slash in the string ( not the first, because of greedy matching. )
 

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TRIM(3) 								 1								   TRIM(3)

trim - Strip whitespace (or other characters) from the beginning and end of a string

SYNOPSIS
string trim (string $str, [string $character_mask = " 0r B"]) DESCRIPTION
This function returns a string with whitespace stripped from the beginning and end of $str. Without the second parameter, trim(3) will strip these characters: o " " (ASCII 32 ( 0x20)), an ordinary space. o " " (ASCII 9 ( 0x09)), a tab. o " " (ASCII 10 ( 0x0A)), a new line (line feed). o " " (ASCII 13 ( 0x0D)), a carriage return. o "" (ASCII 0 ( 0x00)), the NUL-byte. o "x0B" (ASCII 11 ( 0x0B)), a vertical tab. PARAMETERS
o $str - The string that will be trimmed. o $character_mask - Optionally, the stripped characters can also be specified using the $character_mask parameter. Simply list all characters that you want to be stripped. With .. you can specify a range of characters. RETURN VALUES
The trimmed string. EXAMPLES
Example #1 Usage example of trim(3) <?php $text = " These are a few words :) ... "; $binary = "x09Example stringx0A"; $hello = "Hello World"; var_dump($text, $binary, $hello); print " "; $trimmed = trim($text); var_dump($trimmed); $trimmed = trim($text, " ."); var_dump($trimmed); $trimmed = trim($hello, "Hdle"); var_dump($trimmed); $trimmed = trim($hello, 'HdWr'); var_dump($trimmed); // trim the ASCII control characters at the beginning and end of $binary // (from 0 to 31 inclusive) $clean = trim($binary, "x00..x1F"); var_dump($clean); ?> The above example will output: string(32) " These are a few words :) ... " string(16) " Example string " string(11) "Hello World" string(28) "These are a few words :) ..." string(24) "These are a few words :)" string(5) "o Wor" string(9) "ello Worl" string(14) "Example string" Example #2 Trimming array values with trim(3) <?php function trim_value(&$value) { $value = trim($value); } $fruit = array('apple','banana ', ' cranberry '); var_dump($fruit); array_walk($fruit, 'trim_value'); var_dump($fruit); ?> The above example will output: array(3) { [0]=> string(5) "apple" [1]=> string(7) "banana " [2]=> string(11) " cranberry " } array(3) { [0]=> string(5) "apple" [1]=> string(6) "banana" [2]=> string(9) "cranberry" } NOTES
Note Possible gotcha: removing middle characters Because trim(3) trims characters from the beginning and end of a string, it may be confusing when characters are (or are not) removed from the middle. trim('abc', 'bad') removes both 'a' and 'b' because it trims 'a' thus moving 'b' to the beginning to also be trimmed. So, this is why it "works" whereas trim('abc', 'b') seemingly does not. SEE ALSO
ltrim(3), rtrim(3), str_replace(3). PHP Documentation Group TRIM(3)
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