Programming PHP

The 1th character is e
The 2th character is l
The 3th character is l
The 4th character is o
Cleaning Strings
Often, the strings we get from files or users need to be cleaned up before we can use
them. Two common problems with raw data are the presence of extraneous
whitespace, and incorrect capitalization (uppercase versus lowercase).
Removing Whitespace
You can remove leading or trailing whitespace with the trim( ), ltrim( ), and rtrim( )
functions:
$trimmed = trim(string [, charlist ]);
$trimmed = ltrim(string [, charlist ]);
$trimmed = rtrim(string [, charlist ]);
trim( ) returns a copy of string with whitespace removed from the beginning and
the end. ltrim( ) (the l is for left) does the same, but removes whitespace only from
the start of the string. rtrim( ) (the r is for right) removes whitespace only from the
end of the string. The optional charlist argument is a string that specifies all the
characters to strip. The default characters to strip are given in Table 4-3.
Table 4-3. Default characters removed by trim( ), ltrim( ), and rtrim( )
Character ASCII value Meaning
" " 0x20 Space
"\t" 0x09 Tab
"\n" 0x0A Newline (line feed)
"\r" 0x0D Carriage return
"\0" 0x00 NUL-byte
"\x0B" 0x0B Vertical tab
For example:
$title = " Programming PHP \n";
$str_1 = ltrim($title); // $str_1 is "Programming PHP \n"
$str_2 = rtrim($title); // $str_2 is " Programming PHP"
$str_3 = trim($title); // $str_3 is "Programming PHP"
Given a line of tab-separated data, use the charset argument to remove leading or
trailing whitespace without deleting the tabs:
$record = " Fred\tFlintstone\t35\tWilma \n";
$record = trim($record, " \r\n\0\x0B";
// $record is "Fred\tFlintstone\t35\tWilma"
80 | Chapter 4: Strings
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