PHP $_GET Function

Posted by tutor | Posted in PHP Tutorial | Posted on 14-12-2009-05-2008

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$_GET is a built-in function in PHP which is used to collect values in a form where the method is “get”.

Get method is rarely used though, as the information sent from a form with the GET method is visible to everyone in the browser’s address bar.

Also it has a limit on the amount of information that can be sent. All the information is concatenated in a single line and this line is printed on the browser’s address bar.

    For eg:

    <form action=”data.php” method=”post”>
    Name: <input type=”text” name=”username” />
    Address: <input type=”text” name=”address” />
    <input type=”submit” />
    </form>

When the user clicks the “Submit” button, the URL sent to the server could look something like this:

    http://www.goweb99.com/data.php?username=Tutor&address=Capital+Federal

The “data.php” file can now use the $_GET function to collect form data (the names of the form fields will automatically be the keys in the $_GET array):

    For eg:

    <html>
    <body>
    Welcome <?php echo $_GET["username"]; ?> ! to the world of PHP<br />
    You live at <?php echo $_GET["address"]; ?> .
    </body>
    </html>

Get method should not be used when sending passwords or other sensitive information.

However, because the variables are displayed in the URL, it is possible to bookmark the page, which may serve some purpose.

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PHP Operators

Posted by tutor | Posted in PHP Tutorial | Posted on 12-12-2009-05-2008

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Operators are used to manipulate the values or directly or to operate on variables to manipulate values.

All the operators are categorized under the following:

  • Assignment Operators
  • Arithmetic Operators
  • Comparison Operators
  • String Operators

This section lists the different operators available in PHP.

Assignment Operators

Assignment operators assign a value to a variable, or the value of a variable to another variable.

$my_var = 4;
$another_var = $my_var;

Now both $my_var and $another_var contain the value 4.

Assignments can also be used in conjunction with arithmetic operators, which we will be studying later in this tutorial.

Arithmetic Operators

    Operator Description Example
    + Addition 2 + 4
    - Subtraction 6-2
    * Multiplication 5*3
    / Division 15/3
    % Modulus 43%10
$addition= 2+3;
$subtraction= 3-2;
$multiplication= 2*3;
$division= 22/11;
$modulus = 5 % 2;

Comparison Operators

Comparison Operators are used to compare the values of two operators. These operators are used inside conditional statements and evaluate to either true or false. PHP provides all the comparison operators that are provided by other programming language.
Assume: $x = 4 and $y = 5;

    Operator Description Example Result
    == Equal To $x == $y false
    != Not Equal To $x != $y true
    < Less Than $x < $y true
    > Greater Than $x > $y false
    <= Less Than or Equal To $x <= $y true
    >= Greater Than or Equal To $x >= $y false

String Operators

As we have learned before the dot operator is used to concatenate or join two strings.

$a_string=”Hello”;
$b_string=” Tutor”;
$new_string=$a_string . $_string;
Echo $new_string;
Output

Hello Tutor

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Using echo

Posted by tutor | Posted in PHP Tutorial | Posted on 11-12-2009-05-2008

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As we used in previous pages, the PHP command echo is a way to uotput text to the web browser. Echo is the most commonly, and most ofetenly used command while working in PHP

We use echo to output a string. You can either use a variable or the string itself within quotes.

For eg:

<?php
$myString = “PHP”;
echo $myString;
echo “<h5>PHP is too good!</h5>”;
?>

Output:

PHP
PHP is too good!

The text that we output through echo is sent to the user in the form of a web page. So we can also use HTML tags inside the echo command,

Careful When Echoing Quotes!

It seems very good to be able to output HTML with PHP. However, you must be careful when using HTML code, when it contains quotes. Echo uses quotes to mark the beginning and end of the string, so you must not use quotes other than at the starting and the ending. If its necessary to use quotes inside echo you must use one of these methods

Use escape sequence to escape your quotes from echo ie just put a backslash directly before the quotation mark, like \”

Use single quotes (apostrophes) for quotes inside your string like ‘ ’.

<?php
Echo “<h5 class=”specialH5”>I Love PHP!</h5> //doesn’t work
echo “<h5 class=\”specialH5\”>I love using PHP!</h5>”; //works
?>

Echoing Variables

While echoing variables in PHP no quotations are required. They are written directly with echo as:

For eg:

<?php
$my_string = “PHP is too good  ”;
$my_number = 4;
$my_letter = U;
echo $my_string;
echo $my_number;
echo $my_letter;
?>

Output:

PHP is too good 4U

Echoing Variables and Text Strings

You can also place variables inside of double-quoted strings. This tells the PHP interpreter to output the string value of the variable to be printed in the place of the variable.

For eg:

<?php
$my_string = “PHP is too good”;
echo “$my_string to use <br />”;
echo “PHP is a scripting language $my_string <br />”;
echo “PHP is a scripting language $my_string to use”;
?>

Output:

PHP is too good to use
PHP is a scripting language PHP is too good
PHP is a scripting language PHP is too good to use

Using variables saves time and provide reusability, you don’t need to retype the whole string over and again whenever you want to use it. With variables you can just use the variable whrever theres a need to use the same variable. It makes the code readable.

You should always use double quotes with string variables, as single quotes will not give the value of the string rather it will just print the variable name like

$my_string

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Embedding PHP in HTML

Posted by tutor | Posted in PHP Tutorial | Posted on 11-12-2009-05-2008

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PHP is almost always used with HTML. PHP scripts are embedded inside HTML pages anywhere in the body section.

A simple HTML page with PHP scripts looks like this:

<html>
<head>
<title> Embedding PHP in HTML</title>
</head>
<body>
<?php
echo ”It’s so good to be here!!!”;
?>
</body>
</html>
Output:

It’s so good to be here!!!

Echo is a PHP command to output string on the web page.
Echo is a vast topic so we will be discussing it later in this tutorial.

The Semicolon

Each line of PHP code ends with a semicolon. Semicolon is the PHP delimiter.

PHP will show an error if the semicolon is missed in any line.

echo ”It’s so good to be here!!!”;

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