String Theory - Getting Into Position (
Page 4 of 7 )
You can use the
case-sensitive strpos() function to locate the first occurrence of a character
in a string,
<?
$str = "Robin Hood and his band of merry men";
// returns 0
echo strpos($str, "R");
?>
and the strrpos() function to locate its last occurrence.
<?
$str = "Robin Hood and his band of merry men";
// returns 33
echo strrpos($str, "m");
?>
The substr_count() function comes in handy if you need to
know how many times a specific patter recurs in a string.
<?
$str = "'tis said that the is the most common word in the English language,
and e is the most common letter";
// returns 4
echo substr_count($str, "the");
?>
The strstr() function scans a string for a particular pattern
and returns the contents of that string from the point onwards (for a
case-insensitive version, try stristr()).
<?
$str = "As Mulder keeps saying, the truth is out there";
// returns "the truth is out there"
echo strstr($str, "the");
?>
If you need to compare two strings, the strcmp() function
performs a case-sensitive binary comparison of two strings, returning a negative
value if the first is "less" than the second, a positive value if it's the other
ways around, and zero if both strings are "equal". Take a look at a couple of
examples to see what this means:
<?
// returns -1 because a < s
echo strcmp("apple", "strawberry");
// returns 1 because u > p (s == s)
echo strcmp("superman", "spiderman");
// returns 0
echo strcmp("ape", "ape");
?>
You can perform a case-insensitive comparison with the
strcasecmp() function, or adopt a different approach with the very cool "natural
order" comparison, which compares strings the way humans (rather than computers)
would.
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