Recipe 1.9 Trimming Blanks from a String
1.9.1 Problem
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.
1.9.2 Solution
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']);
1.9.3 Discussion
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.
1.9.4 See Also
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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