PHP for Loop
Mastering PHP for Loop: A Comprehensive Tutorial with Examples
Introduction:
Welcome to our in-depth tutorial on PHP for loops! In this lesson, you will learn the fundamentals of using the for loop in PHP, a powerful construct for iteration. We’ll cover the syntax, usage, and practical examples, including the break and continue statements. By the end of this tutorial, you’ll be equipped with the knowledge to efficiently use for loops in your PHP applications.
In PHP, the for loop is used to iterate over a range of values or elements.
It has the following syntax:
for (initialization; condition; increment/decrement) {
// code to be executed
}Here’s a breakdown of each part:
Initialization: This part is executed once at the beginning and is used to initialize a counter variable.
Condition: It is evaluated before each iteration. If the condition is true, the loop continues; otherwise, it terminates.
Increment/Decrement: This part is executed after each iteration and is used to update the counter variable.
Code to be executed: This is the block of code that will be executed in each iteration of the loop.
Here’s a simple example of a for loop that prints numbers from 1 to 5:
<?php
for ($i = 1; $i <= 5; $i++) {
echo $i . " ";
}
?>This will output:
1 2 3 4 5
You can modify the initialization, condition, and increment/decrement parts to suit your specific needs. The for loop is a versatile construct and can be used in various scenarios, such as iterating over arrays, generating sequences, etc.
complete example in html with explanation
Below is a complete example of using a PHP for loop within an HTML file.
In this example, we’ll create a simple HTML page that uses a for loop to generate an ordered list of numbers from 1 to 5.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>PHP For Loop Example</title>
</head>
<body>
<h2>Numbers from 1 to 5 using PHP For Loop</h2>
<ol>
<?php
// PHP for loop to generate numbers from 1 to 5
for ($i = 1; $i <= 5; $i++) {
echo "<li>$i</li>";
}
?>
</ol>
</body>
</html>Explanation:
<!DOCTYPE html>: This declaration specifies the document type and version of HTML.
<html lang=”en”>: The opening tag for the HTML document, indicating the language is English.
<head>: Contains metadata about the HTML document, including character set and viewport settings.
<title>: Sets the title of the HTML document, which is displayed in the browser’s title bar or tab.
<body>: Contains the content of the HTML document.
<h2>: A heading that provides a title for the page section.
<ol>: An ordered list HTML element.
<?php ?>: PHP code is embedded within these tags.
The for loop generates list items (<li>) inside the ordered list (<ol>) with numbers from 1 to 5.
$i: The loop variable that represents the current iteration.
echo “<li>$i</li>”;: Prints each number within an <li> element.
When you open this HTML file in a web browser, you will see a numbered list from 1 to 5 generated by the PHP for loop.
PHP for Loop with The break Statement
The break statement in PHP is used to exit a loop prematurely.
Here’s an example of a for loop with a break statement:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>PHP For Loop with Break Statement</title>
</head>
<body>
<h2>Numbers from 1 to 5 using PHP For Loop with Break Statement</h2>
<ol>
<?php
// PHP for loop to generate numbers from 1 to 5
for ($i = 1; $i <= 5; $i++) {
// If $i is greater than 3, exit the loop
if ($i > 3) {
break;
}
echo "<li>$i</li>";
}
?>
</ol>
</body>
</html>Explanation:
- This example is similar to the previous one, with the addition of a break statement.
- The for loop iterates from 1 to 5.
- Inside the loop, there is an if statement that checks if the current value of $i is greater than 3.
- If $i is greater than 3, the break statement is executed, and the loop is exited prematurely.
- As a result, only the numbers 1, 2, and 3 are printed within the ordered list.
When you open this HTML file in a web browser, you will see a numbered list containing only the numbers 1, 2, and 3, as the loop breaks when $i becomes greater than 3.
The PHP for Loop with The continue Statement
The continue statement in PHP is used to skip the rest of the code inside a loop for the current iteration and move to the next iteration.
Here’s an example of a for loop with a continue statement:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>PHP For Loop with Continue Statement</title>
</head>
<body>
<h2>Numbers from 1 to 5 using PHP For Loop with Continue Statement</h2>
<ol>
<?php
// PHP for loop to generate numbers from 1 to 5
for ($i = 1; $i <= 5; $i++) {
// If $i is equal to 3, skip this iteration using continue
if ($i == 3) {
continue;
}
echo "<li>$i</li>";
}
?>
</ol>
</body>
</html>Explanation:
- This example is similar to the previous ones, but it uses a continue statement.
- The for loop iterates from 1 to 5.
- Inside the loop, there is an if statement that checks if the current value of $i is equal to 3.
- If $i is equal to 3, the continue statement is executed, and the rest of the code inside the loop for the current iteration is skipped. The loop then proceeds to the next iteration.
- As a result, the number 3 is skipped, and the ordered list contains the numbers 1, 2, 4, and 5.
When you open this HTML file in a web browser, you will see a numbered list containing the numbers 1, 2, 4, and 5, with the number 3 skipped due to the continue statement.
An application by this lesson with explanation
In this application, we’ll generate an HTML page that displays a list of numbers from 1 to 5 using a for loop. We’ll also incorporate the break and continue statements to demonstrate how they work.
Create a new file named index.php.
Add the following code to index.php:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>PHP Loop Examples</title>
</head>
<body>
<h2>Numbers from 1 to 5 using PHP For Loop</h2>
<h3>Using break statement:</h3>
<ol>
<?php
// PHP for loop to generate numbers from 1 to 5
for ($i = 1; $i <= 5; $i++) {
// If $i is greater than 3, exit the loop
if ($i > 3) {
break;
}
echo "<li>$i</li>";
}
?>
</ol>
<h3>Using continue statement:</h3>
<ol>
<?php
// PHP for loop to generate numbers from 1 to 5
for ($i = 1; $i <= 5; $i++) {
// If $i is equal to 3, skip this iteration using continue
if ($i == 3) {
continue;
}
echo "<li>$i</li>";
}
?>
</ol>
</body>
</html>Explanation:
- The index.php file contains an HTML structure with two sections.
- The first section uses a for loop with a break statement to generate an ordered list of numbers from 1 to 5, but it breaks the loop when the value is greater than 3.
- The second section uses a for loop with a continue statement to generate an ordered list of numbers from 1 to 5, but it skips the iteration when the value is equal to 3.
When you open this file in a web browser (by running a local server or uploading it to a web server), you’ll see a page with two sections: one displaying numbers from 1 to 3 using a break statement, and the other displaying numbers from 1 to 5 with the number 3 skipped using a continue statement.
Quiz about the PHP for loop
Below are 15 quiz questions related to the PHP for loop lesson.
1-What is the purpose of the for loop in PHP?
A) To define functions
B) To iterate over a range of values
C) To create arrays
D) To execute conditional statements
2-Which part of the for loop is executed once at the beginning to initialize a counter variable?
A) Initialization
B) Condition
C) Increment/Decrement
D) Code to be executed
3-What does the break statement do in a loop?
A) Skips the rest of the loop code for the current iteration
B) Continues to the next iteration of the loop
C) Ends the script execution
D) Initializes a counter variable
4-In the context of a for loop, what does the counter variable represent?
A) The loop condition
B) The number of iterations
C) The code to be executed
D) The current iteration
5-Which HTML tag is used to create an ordered list in the provided examples?
A) <ul>
B) <ol>
C) <li>
D) <list>
6-What is the output of the following loop?
for ($i = 1; $i <= 3; $i++) {
echo $i . ” “;
}
A) 1 2 3
B) 3 2 1
C) 1 1 1
D) 2 4 6
7-In the context of a for loop, what happens if the loop condition is false initially?
A) The loop executes indefinitely
B) The loop does not execute at all
C) The loop executes only once
D) The loop condition is ignored
8-What is the purpose of the continue statement in a loop?
A) Exits the loop prematurely
B) Skips the current iteration and moves to the next
C) Ends the script execution
D) Initializes the loop counter
9-Which part of the for loop is evaluated before each iteration to determine whether the loop should continue?
A) Initialization
B) Condition
C) Increment/Decrement
D) Code to be executed
10-How can you create an unordered list in HTML?
A) <ol>
B) <ul>
C) <li>
D) <dl>
11-What is the purpose of the echo statement in PHP?
A) To create arrays
B) To print output to the browser
C) To define functions
D) To execute conditional statements
12-In the context of a for loop, what happens if the loop condition is never false?
A) The loop executes only once
B) The loop executes indefinitely
C) The loop skips iterations
D) The loop condition is ignored
13-How can you embed PHP code within HTML?
A) Using <script> tags
B) Using <php> tags
C) Using <?php ?> tags
D) Using <code> tags
14-What is the purpose of the <!DOCTYPE html> declaration in an HTML document?
A) Defines a function
B) Specifies the version of HTML
C) Creates an array
D) Executes a conditional statement
15-What does the viewport meta tag in HTML control?
A) Font size
B) Background color
C) Screen dimensions and scaling on mobile devices
D) Image resolution
Answers:
1-B, 2. A, 3. A, 4. D, 5. B, 6. A, 7. B, 8. B, 9. B, 10. B, 11. B, 12. B, 13. C, 14. B, 15. C