How do you get started with PHP?

HelloWorld · #1 (**permalink**) 06-13-2007, 11:49 AM

I've had programming background, but sometimes I'm just confused on where should I start? I've understood some conscept of PHP, but I'm just not sure on how does it work on web application. For example, I want to create a login page:

HTML Code:

<form> <input type="text" id="username"></input> <input type="submit" id="password"></input> </form>

And then, where do you call PHP? I'm sure that it's not like JavaScript right? where you can call it from external, or indented within HEAD tag? How can I process the information based on the ID with PHP? thanx

Lee · #2 (**permalink**) 06-13-2007, 11:55 AM

Quote:

Originally Posted by HelloWorld

I've had programming background, but sometimes I'm just confused on where should I start? I've understood some conscept of PHP, but I'm just not sure on how does it work on web application. For example, I want to create a login page:

HTML Code:

<form> <input type="text" id="username"></input> <input type="submit" id="password"></input> </form>

And then, where do you call PHP? I'm sure that it's not like JavaScript right? where you can call it from external, or indented within HEAD tag? How can I process the information based on the ID with PHP? thanx

You could start <form action="handlingform.php"> at the start then it would carry out the instructions in that php file, at the moment i prefer this.

The other way is if you have a php page with the form on you can do:

PHP Code:

  <?php

If (isset($_GET['password'])){ //password is name of submit button, thats why we use that.
//do statements like add to db here

} else {

echo "table code"; // here echo your table
}

(i dont use id="" all that much, i use name="")
i hope i have done this correctly and that it helps.

HelloWorld · #3 (**permalink**) 06-13-2007, 11:59 AM

Quote:

You could start <form action="handlingform.php"> at the start then it would carry out the instructions in that php file, at the moment i prefer this.

Can't we just add that to display the login form? Because at the beginning, submit button is not pressed right, so shouldn't it display what's within the else statement?

Lee · #4 (**permalink**) 06-13-2007, 12:06 PM

Im not sure you get what i mean, you have a html page, say login.htm and that contains your form:

<form action="handlefile.php">
<input type="text" id="username">
</input>
<input type="submit" id="password">
</input>
</form>

then you have that other file handlefile.php, you see in the above when the button is clicked it will then carry out what is in the php file.

TeraTask · #5 (**permalink**) 06-13-2007, 12:21 PM

Quote:

Originally Posted by Lee

(i dont use id="" all that much, i use name="")

id is important to use if you want to use a scripting language like javascript to access information on the page through the DOM. name is important to use for submitting data as the value of name will be the new variable on the server when the form is submittted.

Now, let's look at

Code:

<form action="handlefile.php"> 
<input type="text" id="username">
</input>
<input type="submit" id="password">
</input> 
</form>

First, rewrite it as

Code:

<form action="login.php" method="post"> 
<input type="text" id="username" name="username" /><br />
<input type="password" id="password" name="password" /><br />
<input type="submit" value="Login" />
</form>

Then, assuming that form is also on login.php, you can access the username and password through $_POST['username'] and $_POST['password'], respectively. Here's an example.

PHP Code:

  <?php
if (strlen($_POST['username']) > 0 && strlen($_POST['password']) > 0) {
  // verify username and password
 if ($_POST['username'] == "allowed_username" && $_POST['password'] == "password") {
  //Take login action
  } else {
   //Take invalid login action
  }
}
?>
 <form action="login.php" method="post"> 
 <input type="text" id="username" name="username" /><br />
 <input type="password" id="password" name="password" /><br />
<input type="submit" value="Login" />
 </form>

Lee · #6 (**permalink**) 06-13-2007, 12:31 PM

Quote:

Originally Posted by TeraTask

the value of name will be the new variable on the server when the form is submittted.

Yes, using name for that bit works fine for me.

and i thought you needed some help, not making examples

HelloWorld · #7 (**permalink**) 06-13-2007, 12:59 PM

what's the difference between

PHP Code:

  strlen

and

PHP Code:

  isset

when do I want use one over the other?

TeraTask · #8 (**permalink**) 06-13-2007, 01:09 PM

strlen tells the length of the string. isset tells only if the variable has been defined. I don't want to process a login if the variable is set - it could be empty. I only want to process the login if the the user actually entered something, so I check to make sure that the string is not empty.

Lee · #9 (**permalink**) 06-13-2007, 01:11 PM

PHP Code:

  strlen()

Is to check the length of something, you place that something inside the brackets and it will check the length, you can then use that to do what you did

PHP Code:

  strlen($_POST['username']) > 0

That checks to see if the username is longer than 0 so is it there?

PHP Code:

  isset()

As far as i know its used, for example to see if the button has been clicked like the example i gave.

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