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there's an error associated with this field. To do so, I use the array_key_exists() func-
tion, which is yet another built-in PHP function. Remember that the keys in $errors are
the names of the fields with errors. So if the $errors array contains an element with the
key name , it means that this field was not valid.
If there is an error with the field, I include the attribute class=”error” in the <label>
tag for the field. When the form is presented, the label will be red, indicating to the user
that she needs to fix that field, even if the user didn't bother to read the list of errors. If
there isn't an error, the normal <label> tag is printed.
When that's done, I just have to print out the name field, but in this case I need to include
the value that was submitted for the field if it's available. I include the value attribute in
my <input> tag, and I use a short tag to include the value of $_POST['name'] as the
value. Inside the expression evaluator, I've wrapped the variable containing the value for
the field in the strip_tags() function. This PHP function automatically removes any
HTML tags from a string, and it's used here to thwart any possible cross-site scripting
attacks a malicious person might employ.
The age field is identical to the name field in every way except its name, so I skip that
and turn instead to the toys field. Here's the code:
<?php if (array_key_exists('toys', $errors)) { ?>
<label for=”toys[]” class=”error”><b> Toys: </b></label>
<?php } else { ?>
<label for=”toys[]”><b> Toys: </b></label>
<?php } ?>
<br />
<?php foreach ($toys as $key => $value) { ?>
<label><input type=”checkbox” name=”toys[]”
<?php if (in_array($key, $_POST['toys'])) { echo 'checked=”checked” '; } ?>
value=”<?= $key ?>” /> <?= $value?> </label><br />
<?php } ?>
As you can see, the code for marking the label for the field as an error is the same for
this field as it was for name . The more interesting section of the code here is the loop that
creates the check boxes. When I was describing the form-processing section of the page,
I explained that I put all the toys inside the array $toys so that I could print out the
check boxes using a loop. There's the loop.
The values in the <input> tags are the keys in the array, and the labels for the check
boxes are the values. I use the associative array version of the foreach loop to copy each
of the key/value pairs in the array into the variables $key and $value . Inside the loop, I
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