You want to remove whitespace from the beginning or end of a string. For example, you want to clean up user input before validating it.
Use ltrim( )
, rtrim( )
, or
trim( )
. ltrim( )
removes
whitespace from the beginning of a string, rtrim( )
from the end of a string, and trim( )
from both the beginning and end of a string:
$zipcode = trim($_REQUEST['zipcode']); $no_linefeed = rtrim($_REQUEST['text']); $name = ltrim($_REQUEST['name']);
For these functions, whitespace is defined as the following characters: newline, carriage return, space, horizontal and vertical tab, and null.
Trimming whitespace off of strings saves storage space and can make
for more precise display of formatted data or text within
<pre>
tags, for example. If you are doing
comparisons with user input, you should trim the data first, so that
someone who mistakenly enters “98052
" as their Zip Code isn’t forced to
fix an error that really isn’t. Trimming before
exact text comparisons also ensures that, for example,
“salami\n” equals
“salami.” It’s
also a good idea to normalize string data by trimming it before
storing it in a database.
The trim( )
functions can also remove
user-specified characters from strings. Pass the characters you want
to remove as a second argument. You can indicate a range of
characters with two dots between the first and last characters in the
range.
// Remove numerals and space from the beginning of the line print ltrim('10 PRINT A$',' 0..9'); // Remove semicolon from the end of the line print rtrim('SELECT * FROM turtles;',';'); PRINT A$ SELECT * FROM turtles
PHP also provides chop( )
as an alias for rtrim( )
.
However, you’re best off using rtrim( )
instead, because PHP’s chop( )
behaves differently than
Perl’s
chop( )
(which is deprecated in favor of
chomp( )
, anyway) and using it can confuse others
when they read your code.
Documentation on trim( )
at
http://www.php.net/trim, ltrim( )
at http://www.php.net/ltrim, and
rtrim( )
at
http://www.php.net/rtrim.
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