PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

118 Chapter 4 String Manipulation and Regular Expressions
strtok() is typically used as follows:
$token = strtok($feedback, ‘“ “);
echo $token.””;
while ($token != “”) {
$token = strtok(“ “);
echo $token.””;
}
As usual, it’s a good idea to check that the customer actually typed some feedback in
the form, using, for example, the empty() function.We have omitted these checks for
brevity.
The preceding code prints each token from the customer’s feedback on a separate
line and loops until there are no more tokens. Empty strings are automatically skipped in
the process.
Using substr()
The substr() function enables you to access a substring between given start and end
points of a string. It’s not appropriate for the example used here but can be useful when
you need to get at parts of fixed format strings.
The substr() function has the following prototype:
string substr(string string, int start[, int length] );
This function returns a substring copied from within string.
The following examples use this test string:
$test = ‘Your customer service is excellent’;
If you call it with a positive number for start (only), you will get the string from the
start position to the end of the string. For example,
substr($test, 1);
returns our customer service is excellent. Note that the string position starts
from 0, as with arrays.
If you call substr() with a negative start (only), you will get the string from the
end of the string minus start characters to the end of the string. For example,
substr($test, -9);
returns excellent.