The method of using foreach loop arrays in PHP has the following key points: 1. The basic syntax is foreach ($array as $value), which is suitable for cases where only values ??need to be processed; 2. If you need to process keys and values ??at the same time, use foreach ($array as $key => $value); 3. For index arrays such as $fruits, you can get values ??one by one through foreach ($fruits as $fruit); 4. In associative arrays such as $user, use the $field => $value structure to obtain keys and values ??at the same time; 5. To modify the original array elements, you need to pass them through references, that is, use &$num, and execute unset($num) after the loop ends. These methods make array traversal operations clearer and more concise.

Sure, you want to loop through an array in PHP using foreach —it's one of the cleanest and most straightforward ways to handle arrays. Here's how to do it right.

Basic syntax of foreach

The foreach loop is designed specifically for arrays. The general structure looks like this:

 foreach ($array as $value) {
    // Do something with $value
}

If you need both the key and the value (like when working with associated arrays), you use this version:

 foreach ($array as $key => $value) {
    // Now you can use both $key and $value
}

This makes it easy to access each element without worrying about indexes or manually increasing a counter like you would with for loops.

How to use foreach with indexed arrays

Say you have a simple list of items:

 $fruits = ['apple', 'banana', 'cherry'];

You can loop through them like so:

 foreach ($fruits as $fruit) {
    echo "I like $fruit.<br>";
}

Each time through the loop, $fruit takes on the value of the current item in the array. This works great for displaying lists, processing form inputs, or applying the same operation to every item.

One thing to note: variable names matter. Don't reuse $fruit somewhere else inside the loop unless you really mean to.

Working with associated arrays

When your array has keys and values ??(like settings or user data), you'll want to capture both:

 $user = [
    'name' => 'Alice',
    'age' => 30,
    'role' => 'Admin'
];

foreach ($user as $field => $value) {
    echo "Field: $field, Value: $value<br>";
}

This way, you get both the label ( name , age ) and what they contain ( Alice , 30 ). It's especially useful for things like dynamically generating HTML forms or logging data structures.

• If you only need the keys, just use $key => $value but work only with $key .
• If you only care about the values, ignore the key part entirely.

Modifying array elements during iteration

By default, the $value in foreach ($array as $value) is a copy. So if you try to change $value , the original array stays the same.

If you do want to modify the actual array elements, you need to pass by reference using & :

 foreach ($numbers as &$num) {
    $num *= 2;
}
unset($num); // Always unset after using &

That doubles each number in the original array. Just remember to unset($num) afterward—otherwise, $num will still refer to the last element, which might cause bugs later.

And that's basically it. foreach keeps array looping simple once you get the hang of it.

The above is the detailed content of How do I iterate over an array in PHP using foreach?. For more information, please follow other related articles on the PHP Chinese website!