PHP switch Statement
Mastering PHP Switch Statement-A Comprehensive Guide for Web Developers
Introduction:
Explore the power of the PHP switch statement with our in-depth tutorial. Learn how to efficiently handle multiple conditions, streamline code, and make your PHP scripts more readable. Dive into practical examples and enhance your web development skills.
The switch statement in PHP is used to select one of many blocks of code to be executed. It is an alternative to a series of if statements.
The basic syntax of the switch statement looks like this:
switch (expression) {
case label1:
// code to be executed if expression matches label1
break;
case label2:
// code to be executed if expression matches label2
break;
// more cases as needed
default:
// code to be executed if none of the cases match the expression
}Explanation:
Here’s a breakdown of the components:
expression: This is the value that you want to compare. The switch statement evaluates this expression once and then compares it with the values in the case labels.
case label1, case label2, etc.: These are the different cases or values that you want to compare with the expression. If the expression matches a case value, the corresponding block of code is executed.
break: This keyword is used to exit the switch statement. After a matching case is found and its code block is executed, the break statement is used to terminate the switch statement. If you omit the break, execution will “fall through” to the next case.
default: This is an optional case that is executed if none of the cases match the expression.
Here’s an example:
$day = "Monday";
switch ($day) {
case "Monday":
echo "It's the start of the week.";
break;
case "Friday":
echo "TGIF!";
break;
default:
echo "It's a regular day.";
}In this example, if $day is “Monday,” it will output “It’s the start of the week.” If $day is “Friday,” it will output “TGIF!” If neither, it will output “It’s a regular day.”
complete example in html with explanation
- Let’s create a simple HTML page with a switch statement in PHP.
- In this example, we’ll use a form to take input for a day of the week, and then use a switch statement in PHP to provide a message based on the selected day.
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Day of the Week Greeting</title> </head> <body> <h1>Day of the Week Greeting</h1> <form method="post" action="greet.php"> <label for="day">Select a day:</label> <select name="day" id="day"> <option value="Monday">Monday</option> <option value="Tuesday">Tuesday</option> <option value="Wednesday">Wednesday</option> <option value="Thursday">Thursday</option> <option value="Friday">Friday</option> <option value="Saturday">Saturday</option> <option value="Sunday">Sunday</option> </select> <button type="submit">Get Greeting</button> </form> </body> </html>
Explanation:
- The HTML page contains a form with a dropdown menu (<select>) allowing the to choose a day of the week.
- The form uses the HTTP POST method and submits the data to a file named “greet.php” (specified in the action attribute of the <form> tag).
Now, let’s create the “greet.php” file with the PHP code that uses the switch statement to provide a greeting based on the selected day.
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Check if the form is submitted using POST method
// Retrieve the selected day from the form
$selectedDay = $_POST["day"];
// Use a switch statement to provide a greeting based on the selected day
switch ($selectedDay) {
case "Monday":
$greeting = "It's the start of the week.";
break;
case "Friday":
$greeting = "TGIF!";
break;
default:
$greeting = "It's a regular day.";
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Greeting Result</title>
</head>
<body>
<h1>Greeting Result</h1>
<?php
// Display the greeting if it is set
if (isset($greeting)) {
echo "<p>{$greeting}</p>";
} else {
echo "<p>Please select a day to get a greeting.</p>";
}
?>
</body>
</html>Explanation:
- In “greet.php,” we use $_POST[“day”] to retrieve the selected day from the form.
- We then use a switch statement to determine the appropriate greeting based on the selected day.
- The resulting greeting is displayed in the HTML page. If no day is selected, a message prompts the to choose a day.
- This example demonstrates how to use a switch statement in PHP within the context of an HTML form.
Another example
- Let’s create another example using a simple PHP switch statement within an HTML page.
- In this example, we’ll take a numeric input from the and use a switch statement to determine whether the number represents a weekday or a weekend day.
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Weekday or Weekend Checker</title> </head> <body> <h1>Weekday or Weekend Checker</h1> <form method="post" action="check_day.php"> <label for="dayNumber">Enter a number (1-7):</label> <input type="number" name="dayNumber" id="dayNumber" min="1" max="7" required> <button type="submit">Check</button> </form> </body> </html>
Explanation:
- The HTML page contains a form with a numeric input field (<input type=”number”>) allowing the to enter a number representing a day of the week.
- The form uses the HTTP POST method and submits the data to a file named “check_day.php” (specified in the action attribute of the <form> tag).
Now, let’s create the “check_day.php” file with the PHP code that uses the switch statement to determine whether the entered number represents a weekday or a weekend day.
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Check if the form is submitted using POST method
// Retrieve the entered day number from the form
$dayNumber = $_POST["dayNumber"];
// Use a switch statement to check whether the number represents a weekday or weekend day
switch ($dayNumber) {
case 1:
case 2:
case 3:
case 4:
case 5:
$result = "Weekday";
break;
case 6:
case 7:
$result = "Weekend";
break;
default:
$result = "Invalid day number. Please enter a number between 1 and 7.";
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Result</title>
</head>
<body>
<h1>Result</h1>
<?php
// Display the result if it is set
if (isset($result)) {
echo "<p>The entered number represents a {$result} day.</p>";
} else {
echo "<p>Please enter a number to check whether it represents a weekday or weekend day.</p>";
}
?>
</body>
</html>Explanation:
- In “check_day.php,” we use $_POST[“dayNumber”] to retrieve the entered day number from the form.
- We then use a switch statement to check whether the number represents a weekday or a weekend day.
- The resulting information is displayed in the HTML page. If no number is entered or if the entered number is invalid, a message prompts the to enter a valid number.
This example demonstrates how to use a switch statement in PHP to determine the type of day (weekday or weekend) based on input within the context of an HTML form.
The break Keyword
In PHP, the break keyword is used in control structures like switch, while, do-while, and for to exit the current loop or switch statement and resume execution at the next statement after the loop or switch.
Let’s focus on the break keyword within the context of a switch statement:
$day = "Monday";
switch ($day) {
case "Monday":
echo "It's the start of the week.";
break; // The break statement exits the switch statement here
case "Friday":
echo "TGIF!";
break;
default:
echo "It's a regular day.";
}Explanation:
- In the example above, if the value of $day is “Monday,” the code block under the first case will be executed, and then the break statement will exit the switch statement.
- If you omit the break, the execution would “fall through” to the next case, and the code under the “Friday” case would also be executed even if it doesn’t match the current value of $day.
Here’s an example without break:
$day = "Monday";
switch ($day) {
case "Monday":
echo "It's the start of the week.";
// No break, so execution falls through to the next case
case "Friday":
echo "TGIF!";
break;
default:
echo "It's a regular day.";
}- In this case, if $day is “Monday,” both “It’s the start of the week.” and “TGIF!” would be printed because there’s no break after the “Monday” case.
- The break statement is crucial for controlling the flow of a switch statement, ensuring that only the code corresponding to the matching case is executed, and the switch statement is exited afterward.
complete code example in html with explanation
- Let’s create a complete example with an HTML form where a selects a day of the week, and a PHP switch statement is used to provide a message based on the selected day.
- This example will emphasize the use of the break statement within the context of a switch statement.
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Day of the Week Greeting</title> </head> <body> <h1>Day of the Week Greeting</h1> <form method="post" action="greet.php"> <label for="day">Select a day:</label> <select name="day" id="day"> <option value="Monday">Monday</option> <option value="Tuesday">Tuesday</option> <option value="Wednesday">Wednesday</option> <option value="Thursday">Thursday</option> <option value="Friday">Friday</option> <option value="Saturday">Saturday</option> <option value="Sunday">Sunday</option> </select> <button type="submit">Get Greeting</button> </form> </body> </html>
Explanation of the HTML code:
- The HTML page contains a form with a dropdown menu (<select>) allowing the to choose a day of the week.
- The form uses the HTTP POST method and submits the data to a file named “greet.php” (specified in the action attribute of the <form> tag).
Now, let’s create the “greet.php” file with the PHP code that uses the switch statement to provide a greeting based on the selected day, along with explanations.
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Check if the form is submitted using POST method
// Retrieve the selected day from the form
$selectedDay = $_POST["day"];
// Use a switch statement to provide a greeting based on the selected day
switch ($selectedDay) {
case "Monday":
$greeting = "It's the start of the week.";
break; // Exit the switch statement after this case
case "Friday":
$greeting = "TGIF!";
break; // Exit the switch statement after this case
default:
$greeting = "It's a regular day.";
// No break here, as this is the last case
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Greeting Result</title>
</head>
<body>
<h1>Greeting Result</h1>
<?php
// Display the greeting if it is set
if (isset($greeting)) {
echo "<p>{$greeting}</p>";
} else {
echo "<p>Please select a day to get a greeting.</p>";
}
?>
</body>
</html>Explanation of the PHP code:
- We use $_POST[“day”] to retrieve the selected day from the form.
- The switch statement checks the value of the selected day and provides a specific greeting for “Monday” and “Friday.” For other days, it provides a default greeting.
- The break statement is used after each case to exit the switch statement. Without break, the execution would continue to the next case.
- In the default case, there is no break since it’s the last case. After executing the default code block, the control naturally exits the switch statement.
- This example demonstrates how the break statement is used in a switch statement to control the flow and ensure that only the relevant code block is executed.
The default Keyword
- In PHP, the default keyword is used as part of the switch statement.
- The switch statement allows you to evaluate a variable or an expression against multiple possible values, and the default case is used to specify the code that should be executed if none of the cases match the evaluated value.
Here’s the basic syntax of a switch statement with the default case:
$variable = /* some value */;
switch ($variable) {
case value1:
// code to be executed if $variable is equal to value1
break;
case value2:
// code to be executed if $variable is equal to value2
break;
// more cases as needed
default:
// code to be executed if none of the cases match $variable
}In the example above, if none of the case values matches the value of $variable, the code within the default block will be executed.
Here’s a simple example using the default case:
$day = "Saturday";
switch ($day) {
case "Monday":
echo "It's the start of the week.";
break;
case "Friday":
echo "TGIF!";
break;
default:
echo "It's a regular day.";
}Explanation:
- In this example, if the value of $day is neither “Monday” nor “Friday,” the code within the default block will be executed, and it will echo “It’s a regular day.”
- The default case is optional, and you can choose to omit it if you don’t need to provide specific code for the scenario when none of the case values match. However, it is often a good practice to include a default case to handle unexpected or unspecified values.
An application by this lesson
- let’s create a simple web application using HTML and PHP that allows s to input their name and select a mood from a dropdown menu.
- The PHP code will then generate a personalized greeting based on their selected mood. We’ll also include some CSS for basic styling.
Create the HTML file (index.html):
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Greeting App</title> <link rel="stylesheet" href="styles.css"> </head> <body> <div class="container"> <h1>Welcome to the Greeting App</h1> <form method="post" action="greet.php"> <label for="name">Your Name:</label> <input type="text" name="name" id="name" required> <label for="mood">Select your mood:</label> <select name="mood" id="mood"> <option value="happy">Happy </option> <option value="sad">Sad </option> <option value="excited">Excited </option> <option value="calm">Calm </option> </select> <button type="submit">Get Greeting</button> </form> </div> </body> </html>
Create the CSS file (styles.css):
body {
font-family: Arial, sans-serif;
background-color: #f4f4f4;
margin: 0;
padding: 0;
display: flex;
align-items: center;
justify-content: center;
height: 100vh;
}
.container {
background-color: #fff;
padding: 20px;
border-radius: 8px;
box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}
form {
display: flex;
flex-direction: column;
align-items: center;
}
label {
margin-bottom: 8px;
}
input, select, button {
margin-bottom: 16px;
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
}
button {
background-color: #4caf50;
color: #fff;
cursor: pointer;
}
Create the PHP fFile (greet.php):
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Check if the form is submitted using POST method
// Retrieve the name and mood from the form
$name = $_POST["name"];
$mood = $_POST["mood"];
// Use a switch statement to generate a greeting based on the selected mood
switch ($mood) {
case "happy":
$greeting = "Hello, $name! It's great to see you're happy!";
break;
case "sad":
$greeting = "Hello, $name. Cheer up! Things will get better.";
break;
case "excited":
$greeting = "Wow, $name! Exciting times ahead!";
break;
case "calm":
$greeting = "Hello, $name. Stay calm and enjoy your day.";
break;
default:
$greeting = "Hello, $name! Hope you're having a good day!";
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Greeting Result</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<div class="container">
<h1>Greeting Result</h1>
<?php
// Display the greeting if it is set
if (isset($greeting)) {
echo "<p>{$greeting}</p>";
} else {
echo "<p>Please fill out the form to get a personalized greeting.</p>";
}
?>
<a href="index.html">Go Back</a>
</div>
</body>
</html>Explanation:
- The HTML file (index.html) contains a form where s can input their name and select a mood from a dropdown menu. The form is submitted to greet.php for processing.
- The CSS file (styles.css) provides some basic styling to make the application visually appealing.
- The PHP file (greet.php) processes the form data, uses a switch statement to generate a greeting based on the selected mood, and then displays the result.
To run this application:
- Save the HTML, CSS, and PHP code in separate files (index.html, styles.css, greet.php) within the same directory.
- Set up a local server (e.g., using XAMPP, WampServer, or a similar tool).
- Place the files in the document root of your local server.
- Open your web browser.Access the application by navigating to:
- http://localhost/your-folder-name/index.html
- Fill out the form, submit it, and see the personalized greeting on the result page.
Another application
Let’s create another simple web application using HTML and PHP. This time, we’ll build a basic calculator that allows s to perform addition, subtraction, multiplication, and division. The application will take two numbers and an operation from the , and then display the result.
Create the HTML file (calculator.html):
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Simple Calculator</title> <link rel="stylesheet" href="calculator.css"> </head> <body> <div class="container"> <h1>Simple Calculator</h1> <form method="post" action="calculate.php"> <label for="num1">Enter first number:</label> <input type="number" name="num1" id="num1" required> <label for="operation">Select operation:</label> <select name="operation" id="operation" required> <option value="add">Addition (+)</option> <option value="subtract">Subtraction (-)</option> <option value="multiply">Multiplication (*)</option> <option value="divide">Division (/)</option> </select> <label for="num2">Enter second number:</label> <input type="number" name="num2" id="num2" required> <button type="submit">Calculate</button> </form> </div> </body> </html>
Create the CSS file (calculator.css):
body {
font-family: Arial, sans-serif;
background-color: #f4f4f4;
margin: 0;
padding: 0;
display: flex;
align-items: center;
justify-content: center;
height: 100vh;
}
.container {
background-color: #fff;
padding: 20px;
border-radius: 8px;
box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}
form {
display: flex;
flex-direction: column;
align-items: center;
}
label {
margin-bottom: 8px;
}
input, select, button {
margin-bottom: 16px;
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
}
button {
background-color: #4caf50;
color: #fff;
cursor: pointer;
}
Create the PHP file (calculate.php):
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Check if the form is submitted using POST method
// Retrieve the form data
$num1 = $_POST["num1"];
$num2 = $_POST["num2"];
$operation = $_POST["operation"];
// Initialize the result variable
$result = 0;
// Perform the selected operation
switch ($operation) {
case "add":
$result = $num1 + $num2;
break;
case "subtract":
$result = $num1 - $num2;
break;
case "multiply":
$result = $num1 * $num2;
break;
case "divide":
if ($num2 != 0) {
$result = $num1 / $num2;
} else {
$result = "Cannot divide by zero";
}
break;
default:
$result = "Invalid operation";
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Calculation Result</title>
<link rel="stylesheet" href="calculator.css">
</head>
<body>
<div class="container">
<h1>Calculation Result</h1>
<?php
// Display the result
echo "<p>The result of the calculation is: $result</p>";
?>
<a href="calculator.html">Go Back</a>
</div>
</body>
</html>Explanation:
- The HTML file (calculator.html) contains a form where s can input two numbers, select an operation (addition, subtraction, multiplication, or division), and then submit the form to calculate.php for processing.
- The CSS file (calculator.css) provides basic styling to make the calculator visually appealing.
- The PHP file (calculate.php) processes the form data, performs the selected mathematical operation using a switch statement, and displays the result.
An application about PHP switch Statement with explanation
- Let’s create a simple web application using HTML and PHP that utilizes the PHP switch statement.
- This application will take a user’s choice of a fruit and provide information about the selected fruit using a switch statement.
HTML File (index.html):
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Fruit Information App</title> <link rel="stylesheet" href="styles.css"> </head> <body> <div class="container"> <h1>Fruit Information App</h1> <form method="post" action="fruit_info.php"> <label for="fruit">Select a fruit:</label> <select name="fruit" id="fruit"> <option value="apple">Apple</option> <option value="banana">Banana</option> <option value="orange">Orange</option> <option value="grape">Grape</option> </select> <button type="submit">Get Information</button> </form> </div> </body> </html>
CSS File (styles.css):
body {
font-family: Arial, sans-serif;
background-color: #f4f4f4;
margin: 0;
padding: 0;
display: flex;
align-items: center;
justify-content: center;
height: 100vh;
}
.container {
background-color: #fff;
padding: 20px;
border-radius: 8px;
box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}
form {
display: flex;
flex-direction: column;
align-items: center;
}
label {
margin-bottom: 8px;
}
select, button {
margin-bottom: 16px;
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
}
button {
background-color: #4caf50;
color: #fff;
cursor: pointer;
}PHP File (fruit_info.php):
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Check if the form is submitted using POST method
// Retrieve the selected fruit from the form
$selectedFruit = $_POST["fruit"];
// Use a switch statement to provide information about the selected fruit
switch ($selectedFruit) {
case "apple":
$info = "Apples are a good source of fiber and vitamin C.";
break;
case "banana":
$info = "Bananas are rich in potassium and provide a quick energy boost.";
break;
case "orange":
$info = "Oranges are known for their high vitamin C content and antioxidants.";
break;
case "grape":
$info = "Grapes are packed with antioxidants and are a great snack option.";
break;
default:
$info = "Please select a valid fruit.";
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Fruit Information</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<div class="container">
<h1>Fruit Information</h1>
<?php
// Display the information if it is set
if (isset($info)) {
echo "<p>{$info}</p>";
} else {
echo "<p>Please select a fruit to get information.</p>";
}
?>
<a href="index.html">Go Back</a>
</div>
</body>
</html>- Explanation:
The HTML file (index.html) contains a form where users can select a fruit from a dropdown menu and submit the form to fruit_info.php for processing. - The CSS file (styles.css) provides basic styling to make the application visually appealing.
- The PHP file (fruit_info.php) processes the form data, uses a switch statement to provide information about the selected fruit, and then displays the result.
Quiz about :PHP switch Statement
Here’s a quiz focused on the PHP switch statement:
Quiz: PHP Switch Statement
1-What is the primary purpose of the PHP switch statement?
a) To define constants
b) To execute code based on multiple conditions
c) To create loops
d) To handle exceptions
2-Which keyword is used to exit a case block in a PHP switch statement?
a) stop
b) exit
c) break
d) end
3-What will happen if you omit the break statement after a case in a PHP switch statement?
a) It will result in a syntax error.
b) It will cause an infinite loop.
c) Execution will continue to the next case.
d) It will skip the current case and move to the default case.
4-In a PHP switch statement, what is the purpose of the default case?
a) To handle syntax errors
b) To execute when none of the cases match
c) To define a default value
d) To create a fallback loop
5-Which of the following data types can be used as the switch expression in PHP?
a) Array
b) String
c) Object
d) All of the above
6-In PHP, what happens if none of the cases in a switch statement match the switch expression, and there is no default case?
a) It will result in a syntax error.
b) The switch statement will exit without executing any code.
c) It will trigger a runtime error.
d) It will execute the first case.
7-What is the purpose of the switch keyword in PHP?
a) To define a switch expression
b) To create a loop
c) To start a switch statement
d) To exit a switch statement
8-Can the switch statement in PHP be used for comparisons other than equality?
a) No, it only supports equality comparisons.
b) Yes, it supports various types of comparisons.
c) Only for numeric values.
d) Only for string values.
9-How does the switch statement differ from a series of if-else statements in PHP?
a) It is more efficient for multiple conditions.
b) It can only handle simple conditions.
c) It is slower than if-else statements.
d) It does not support the use of variables.
10-What is the default behavior of a switch statement if there is no break or return statement after a case?
a) It will result in a syntax error.
b) Execution will continue to the next case.
c) It will skip the current case and move to the default case.
d) It will exit the switch statement.
Answers:
1-b) To execute code based on multiple conditions
2-c) break
3-c) Execution will continue to the next case.
4-b) To execute when none of the cases match
5-d) All of the above
6-b) The switch statement will exit without executing any code.
7-c) To start a switch statement
8-b) Yes, it supports various types of comparisons.
9-a) It is more efficient for multiple conditions.
10-b) Execution will continue to the next case.