PHP For Loop: How to Iterate Over Data and Array

PHP for loops are repetitive tasks by nature, such as iterating through an array or executing a block of code multiple times.

In this tutorial, you are going to understand the PHP for loop—how it functions, the right scenarios to use it, and a few practical examples.

What is a PHP For Loop?

The PHP for loop lets you execute a block of code multiple times, continuing as long as a given condition remains true. It is one of the basic loop structures in PHP, alongside while, do-while, and foreach.

Here is the syntax:

for (initialization; condition; increment/decrement) {
    // This is the section where the code block runs
}

• Initialization: This is where you define and initialize a variable, often referred to as the loop counter.
• Condition: The loop keeps running as long as this condition evaluates to true.
• Increment/Decrement: The loop counter is updated after each iteration.

In the next section, we will see how these components come together in action.

How Does a PHP For Loop Work?

Let’s see how it works with an example:

for ($icre = 1; $icre <= 5; $icre++) {
    echo "Iteration number #$icre\n";
}

Here is what is happening step by step:

1. Initialization: The loop starts by setting $icre to 1.
2. Condition: Before running the code block, it checks whether $icre <= 5. If true, it proceeds.
3. Execution: The code inside the loop runs. In this case, it prints Iteration number #$icre.
4. Increment: After the block executes, $icre++ increases $icre by 1.
5. Repeat: The condition is checked again, and the process continues until $icre > 5.

Here is the output:

This is iteration #1
This is iteration #2
This is iteration #3
This is iteration #4
This is iteration #5

The PHP for loop is ideal for situations where you already know the exact number of times a block of code needs to run. For example:

• Generating repetitive HTML elements dynamically.
• Iterating over a range of numbers.
• Performing operations on array indices.

If the number of iterations depends on a condition that might change unpredictably, a while loop or do-while loop would likely be a better choice.

Anyway, in the section below, you will see examples of PHP “for” loop.

Examples of PHP For Loop

Here is an example of how to print a sequence of numbers:

for ($fnumber = 1; $fnumber <= 10; $fnumber++) {
    echo $fnumber . "<br>";
}

This will display the numbers from 1 to 10, each on a new line.

You can use a for loop to calculate the total sum of numbers from 1 to N. Here is how it works:

$sum_tot = 0;
for ($icre = 1; $icre <= 10; $icre++) {
    // Adds the current number to the total su
    $sumsum_tot+= $icre;  
}
echo "The total (sum) of numbers would be from 1 to 10 is $sum_tot.";

Here is the output:

The total sum of numbers from 1 to 10 is calculated as 55.

While foreach is useful for loop arrays, you can also use a for loop for indexed arrays:

$colors = ["Red", "Green", "Blue"];
for ($icre = 0; $icre < count($colors); $icre++) {
    echo $colors[$icre] . "\n";
}

This will print:

Red
Green
Blue

Things get even more interesting when you nest one for loop inside another. Nested loops are often used to handle multidimensional arrays or generate patterns.

Below is an example of how you can build a simple multiplication table using nested loops:

for ($row = 1; $row <= 5; $row++) {
    for ($colm = 1; $colm <= 5; $colm++) {
        echo $row * $colm . "\t";
    }
    echo "<br>";
}

It will print this result:

1   2   3   4   5
2   4   6   8   10
3   6   9   12  15
4   8   12  16  20
5   10  15  20  25

You can skip an iteration and move directly to the next loop cycle. Here is an example:

for ($icre = 1; $icre <= 5; $icre++) {
    if ($icre == 1) {
        // The following line will skip this iteration
        continue; 
    }
    echo $icre . "<br>";
}

Here is the output:

2
3
4
5

You can also combine a for loop with HTML in PHP to dynamically generate HTML, as demonstrated in the following example, which creates a dropdown menu:

echo "<select>";
for ($year = 2000; $year <= 2025; $year++) {
    echo "<option value='$year'>$year</option>";
}
echo "</select>";

This outputs a dropdown list of years from 2000 to 2025.

Let’s summarize it.

Wrapping Up

The PHP for loop is an important tool that enables you to do repetitive tasks in your code. So if you are working with numbers, arrays, or even generating HTML, the for loop is a reliable companion.

So, what will you build with the for loop?