PHP Programming for Beginners. Key Programming Concepts. How to use PHP with MySQL and Oracle databases (MySqli, PDO). Sergey D Skudaev
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($temperature_C) {
Case: 0
$message=“Water freezing point.”;
Break;
Case: 100
$message=“Water boiling point!”:
Break;
Default:
$message=“Neither freezing nor boiling point.”;
}
If we pass in our switch statement variable with the value of 100 we will get Output: “Water boiling point!”
If we pass 0 we will get Output: =“Water freezing point.”
Otherwise, we will get Output: “Neither freezing nor boiling point.”
List
List is a language construction. It is used to assign a list of variables in one operation.
In the line below, I assign array $names from the array example above to a list of variables.
list ($name1, $name2, $name3, $name4, $name5, $name6) = $names;
print ($name5); will print John because it is the 5th name in the array.
Multidimensional Arrays
An example of a two-dimensional array is plane seats. A plane has rows identified by numbers and a few seats in a row identified by letters A, B, C, D, E, and F.
Let us imagine that we have 7 rows with 6 seats in each of the rows. Define an array of seats in a row as $s. Then in two for loops we can create an array of all seats.
$s=array (“A”, “B”, “C”, “D”, “E”, “F”);
for ($i=0; $i <7; $i++) {
$row = $i+1;
for ($j=0; $j <6; $j++) {
$seats [$i] [$j] =$row.$s [$j];
print ($seats [$i] [$j]);
if (($j % 5 ==0) && ($j> 0))
print (”<br>”);
}
}
In an inner J loop, we assign a seat value to the two-dimensional array.
$row = $i +1 because $i starts with 0 and the row starts with 1.
Then we concatenate a row number with a seat letter in $s array.
We insert a line break <br> after every 6 seats.
For that we check if modulo of 5 equals 0. This occurs when $j=5. Since $j starts with 0 we have 6 seats in a row before we insert a break.
Additionally, we check if $j is greater than 0 because 0 modulo 5 gives 0 and creates an extra break we do not want to have.
Output:
1A1B1C1D1E1F
2A2B2C2D2E2F
3A3B3C3D3E3F
4A4B4C4D4E4F
5A5B5C5D5E5F
6A6B6C6D6E6F
7A7B7C7D7E7F
$_GET and $_POST methods
Here you will learn how to use the request variables $_GET and $_POST. These variables provide you with different ways to transfer data from one web page to another. Let’s look at the two methods, starting with GET. First, let’s create a simple HTML form.
$_GET []
<html>
<head>
<title> Form Methods
</title>
</head>
<body>
<form method=“get” action="actionpage.php”>
<p> <input type=“text” name=“greeting” size=“15”> </p>
<p> <input type=“text” name=“name” size=“15”> </p>
<p> <input type=“submit” name=“submit” value=“Salutation”> </p>
</form>
</body>
</html>
Save it as a form_methods.php file in the Apache htdocs/post folder created by you.
And now, we’ll create a actionpage.php file for the Output: data transferred from the form.
<?
echo $_GET [‘greeting’];
echo $_GET [‘name’];
echo”! ”;
?>
Save this file in the same directory as the form_methods.php file. This form looks like the following:
Figure 1. A simple HTML form
Let us enter a greeting and a name and click the Salutation button.
You can see that the data sent from a form with the GET method is displayed in the browser’s address bar:
http://localhost/post/formoutputpage.php? <=>
greeting=Hello&name=Emily&submit=Salutation
The Output web page displays Hello Emily!
$_POST []
Now let’s use the POST method instead of the GET method. Edit form_method.php form.
<html>
<head>
<title> Form Methods </title>
</head>
<body>
<form method=“post” action="formoutputpage.php”>
<p> <input type=“text” name=“greeting” size=“15”> </p>
<p> <input type=“text” name=“name” size=“15”> </p>
<p> <input type=“submit” name=“submit” value=“Salutation”> </p>
</form>
</body>
</html>
Edit formoutputpage.php file as follow:
<?
echo $_POST [‘greeting’];
echo “”. $_POST [‘name’];
echo”! ”;
?>
The browser address bar displays formoutputpage.php, but no data transferred using the POST method is visible, so the web page output remains the same:
Hello Emily!
You don’t have to create a second page to read data submitted with form because it is possible to submit the form to the same page. To do this use super global $_SERVER [“PHP_SELF”].
<?php
$self=$_SERVER [“PHP_SELF”];
$greeting=“”;
$name=“”;
If