ZEND PHP 5 Certification STUDY GUIDE

78 ” Strings And Patterns
Note that string character indices are zero-based—meaning that the first character of
an arbitrary string $s has an index of zero, and the last has an index of strlen($s)-1.
Comparing, Searching and Replacing Strings
Comparison is, perhaps, one of the most common operations performed on
strings. At times, PHP’s type-juggling mechanisms also make it the most maddening—particularly
because strings that can be interpreted as numbers are often transparently
converted to their numeric equivalent. Consider, for example, the following
code:
$string = ’123aa’;
if ($string == 123) {
// The string equals 123
}
You’d expect this comparison to return false, since the two operands are most definitely
not the same. However, PHP first transparently converts the contents of
$string to the integer 123, thus making the comparison true. Naturally, the best way
to avoid this problem is to use the identity operator === whenever you are performing
a comparison that could potentially lead to type-juggling problems.
In addition to comparison operators, you can also use the specialized functions
strcmp() and strcasecmp() to match strings. These are identical, with the exception
that the former is case-sensitive, while the latter is not. In both cases, a result of zero
indicates that the two strings passed to the function are equal:
$str = "Hello World";
if (strcmp($str, "hello world") === 0) {
// We won’t get here, because of case sensitivity
}
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
if (strcasecmp($str, "hello world") === 0) {
// We will get here, because strcasecmp()
// is case-insensitive
}