[RESOLVED] Basic syntax error

samsplug

Im pretty sure I have a basic syntax error because I'm very new to writing PHP... I'm working my way through a PHP and MySQL book by Larry Ullman.

Is there anything blatantly obvious which is wrong with this tag:
<input type="text" name="first_name" size="15" maxlength="15" value="' if (empty($POST['first_name'])) { $row[0]; } else { $POST['first_name']; }'" />

It is a form input.............

Thanks in advance 🙂

NogDog

Basically 2 ways, depending on your preferred approach:

Use [man]echo[/man] (or [man]print[/man]) to output everything:

<?php
echo '<input type="text" name="first_name" size="15" maxlength="15" value="';
if (empty($_POST['first_name'])) { 
   echo $row[0]; 
} else { 
   echo $_POST['first_name']; 
}
echo '" />';

Only go into PHP mode where needed:

<html>
<body>
<input type="text" name="first_name" size="15" maxlength="15" value="<?php
if (empty($_POST['first_name'])) { 
   echo $row[0]; 
} else { 
   echo $_POST['first_name']; 
}
?>" />

Or another way:

<?php
$firstName = (empty($_POST['first_name'])) ? $row[0] : $_POST['first_name'];
echo '<input type="text" name="first_name" size="15" maxlength="15" value="' . $firstName . '" />';

Or if you really want to impress your friends and neighbors:

<?php
printf(
   '<input type="text" name="first_name" size="15" maxlength="15" value="%s" />',
   (empty($_POST['first_name'])) ? $row[0] : $_POST['first_name']
);

And those are by no means all the possibilities. 🙂

samsplug

Thanks for your comprehensive reply NogDog, really helpful for a newb at PHP like myself 😛

I have 2 further questions though:
1. Here is the standard form I am trying to modify the code for:

	// Create the form:
	echo '<form action="edit_user.php" method="post">
<p>First Name: <input type="text" name="first_name" size="15" maxlength="15" value="' . $row[0] . '" /></p>
<p>Last Name: <input type="text" name="last_name" size="15" maxlength="30" value="' . $row[1] . '" /></p>
<p>Email Address: <input type="text" name="email" size="20" maxlength="40" value="' . $row[2] . '"  /> </p>
<p><input type="submit" name="submit" value="Submit" /></p>
<input type="hidden" name="submitted" value="TRUE" />
<input type="hidden" name="id" value="' . $id . '" />
</form>';

Why do the value fields contain a period either side of the variables? I thought periods where for concatenation?

it seems that the first example you provided is the most fitting to the rest of the form's PHP (and the fact that an echo is opened at the start and closed at the end of the forms html tags). Though why is the if statement in the value field preceeded by a semi-colon?

I would be really grateful if someone could answer those two questions 🙂

Arryn

Echo statements are ended with a semicolon. Basically the if statement is injected into the value between the single quotes from the first and second echo. The statement will output one of two values, either the value contained in $row[0] or the value contained in $_POST['first_name']. Even though there's a bunch of gobbledy-gook php stuck in there you are going to get a single output and whatever that output is will wind up being part of what is essentially:

echo '<input type="text" name="first_name" size="15" maxlength="15" value="[output from if]" />';

You could certainly do all of the above in a single echo, but he split it up for clarity.

As to concatenating the variables, you have to leave html, concatenate the value stored in the variable and then go back into html by concatenating the remainder of the html.

samsplug

thanks arryn 🙂
thats clearer now

NogDog

What you will want to strive for as you progress is to as much as possible separate your HTML output from your PHP logic. If you have to keep alternating between HTML text and PHP if/else blocks, nested ifs, switches, etc., it becomes more and more difficult to read you code. That means it becomes more and more difficult to debug or modify your code. (And just imagine if someone else has to debug it!)

Thus you see people using various templating systems, separate "views" (as in a MVC framework), etc. At the very least, for something like this I recommend you set any conditionally set variables first, and then use them in your HTML output.

<?php
// DB code that populates $row, then...
// set your conditional values:
if(empty($_POST['first_name']))
{
   $first_name = $row['first_name'];
}
else
{
   $first_name = $_POST['first_name']
}
// or here's a short-hand way to do the same thing:
$last_name = (empty($_POST['last_name'])) ? $row['last_name'] : $_POST['last_name'];
// now do the output:
echo "
<form action='foo.php' method='post'>
<p><input type='text' name='first_name' value='$first_name' /></p>
<p><input type='text' name='last_name' value='$last_name' /></p>
<p><input type='submit' value='Submit' /></p>
</form>
";

Alternatively, you could drop out of PHP mode for the HTML output, then pop back in as needed to output the variables:

<?php
// DB code that populates $row, then...
// set your conditional values:
$first_name = (empty($_POST['first_name'] ? $row ['first_name'] : $_POST['first_name']
// or here's a short-hand way to do the same thing:
$last_name = (empty($_POST['last_name'])) ? $row['last_name'] : $_POST['last_name'];
// now do the output:
?>
<form action='foo.php' method='post'>
<p><input type='text' name='first_name' value='<?php echo $first_name; ?>' /></p>
<p><input type='text' name='last_name' value='<?php echo $last_name; ?>' /></p>
<p><input type='submit' value='Submit' /></p>
</form>

samsplug

Yeah, I can see the benefits to doing that - thanks NogDog 🙂