Programming PHP

echo("The last comma in the record is at position $pos");
The last comma in the record is at position 18
If you pass a string as the second argument to strrpos( ), only the first character is
searched for. To find the last occurrence of a multicharacter string, reverse the
strings and use strpos( ):
$long = "Today is the day we go on holiday to Florida";
$to_find = "day";
$pos = strpos(strrev ($long), strrev($to_find));
if ($pos === false) {
echo("Not found");
} else {
// $pos is offset into reversed strings
// Convert to offset into regular strings
$pos = strlen($long) - $pos - strlen($to_find);;
echo("Last occurrence starts at position $pos");
}
Last occurrence starts at position 30
Searches returning rest of string
The strstr( ) function finds the first occurrence of a small string in a larger string
and returns from that small string on. For instance:
$record = "Fred,Flintstone,35,Wilma";
$rest = strstr($record, ","); // $rest is ",Flintstone,35,Wilma"
The variations on strstr( ) are:
stristr( )
Case-insensitive strstr( )
strchr( )
Alias for strstr( )
strrchr( )
Find last occurrence of a character in a string
As with strrpos( ), strrchr( ) searches backward in the string, but only for a character,
not for an entire string.
Searches using masks
If you thought strrchr( ) was esoteric, you haven’t seen anything yet. The strspn( )
and strcspn( ) functions tell you how many characters at the beginning of a string
are comprised of certain characters:
$length = strspn(string, charset);
For example, this function tests whether a string holds an octal number:
function is_octal ($str) {
return strspn($str, '01234567') == strlen($str);
}
94 | Chapter 4: Strings
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