Required fields
Some of your fields will be required. In other words,
visitors have to enter something in the field. The following script checks that
a first name was entered:
if (ereg(".", $first_name) == 1)
{
echo "First name: ", "$first_name";
$verify = "OK";
}
else
{
print ("<b>Error:</b> A first name is required.");
$verify = "bad";
}
ereg means "evaluate regular
expression". "Regular expressions" are the UNIX function for finding patterns in
strings of letters and numbers. ereg is followed by parentheses,
and you can put three arguments in the parentheses. The arguments are separated
by commas. The first argument is the pattern to search for, usually surrounded
by quotation marks. The second argument is where ereg is to search,
usually a variable. The third, optional, argument is an array to put matches
into. This argument is a variable.
ereg returns either a "0" (false) or a "1" (true).
The dot . or period is a regular expression wild card meaning
"any character."
(ereg(".", $first_name) == 1) means "the variable '$first_name'
contains anything". If this expression is true, then the first name is printed,
and the variable $verify is set to "OK".
The else argument executes when ereg returns "0"
(false).
There are three other versions of the ereg function.
ereg_replace uses three arguments: the first is the pattern to
search for, the second is the pattern to replace the first pattern, and the
third is where to search (a variable).
eregi is the same as ereg, except that it's not
case-sensitive (i.e., it doesn't differentiate upper- and lower-case letters).
eregi_replace is not case sensitive
Alternative means to the same end
The line if (ereg(".", $first_name) == 1) can be simplified to
if ($first_name). I used the longer form to show how to use
ereg in a simple example.
Checking e-mail addresses
The following ereg arguments test
validity of e-mail addresses:
