How Loops Work in PHP: A Full Leader for Early Persons

PHP loops help you repeat the code block on a condition basis. You can use them to work through ranks or to repeat actions. You can also use them to quit logic -based measures.

In this article, you will learn how PHP loops work and when to use all kinds.

The table of content

• Understand how loops in PHP work

• while Loop in pHP

• do...while Loop in pHP

• for Loop in pHP

• foreach Loop in pHP

• Use break Description

• Use continue Description

• Change the loop array_map() In pHP

• Understand the nesting loop

• Wrap

Let’s start.

Understand how loops in PHP work

A loop allows PHP to run a single set of instructions more than once. It checks a special condition before each run. Then the code runs again if the condition is correct and if the condition is incorrect, it stops.

Loops help reduce the bar code. You can take action on items on a list or test values. Loops allow you to write a block of code and run several times.

PHP provides four main types of loops:

• While

• Do … while

• For

• Forecast

Let’s take a look at each one in detail

while Loop in pHP

While the loop checks that if the condition is valid before the code block is run. If the condition is correct, it runs the block. Then it checks again. The loop repeats until the condition goes wrong.

This is syntax:

while (condition) {
  // code block
}

Here is an example:

$count = 1;
while ($count <= 3) {
  echo "Count: $count\n";
  $count++;
}

This loop begins $count = 1. It prints the price and adds 1 each time. It stops when it stops $count 4 becomes.

It gives you this output:

Count: 1
Count: 2
Count: 3

Here is another example:

$index = 0;
$names = ('Tom', 'Anna', 'Joe');
while ($index < count($names)) {
  echo $names($index) . "\n";
  $index++;
}

This loop prints every name from the row. It uses the index to move in the list.

Output:

Tom
Anna
Joe

So, When should you use? while Loop?

Use A while Loop when you want to test the condition before running the code. This kind of best fits when the loop should not run at all if the condition is wrong from the beginning.

Here is an example:

You ask a user to enter a number. You just want to run your loop at the moment if the number is positive.

$number = getUserInput();

while ($number > 0) {
  echo "You entered: $number\n";
  $number = getUserInput();
}

If the first number is zero or negative, the loop will end. Here it makes sense – you just want the loop to run on the right numbers.

You’ll learn how PHP is do while The loop works in the next section.

do...while Loop in pHP

do...while The loop runs the code block once, then checks the condition. It always runs at least once.

do {
  // code block
} while (condition);

Example:

$start = 5;
do {
  echo "Start: $start\n";
  $start++;
} while ($start < 8);

This loop prints the number from 5 to 7. It examines the condition after the block runs.

Output:

Start: 5
Start: 6
Start: 7

Here is another example:

$retry = 0;
do {
  echo "Attempt $retry\n";
  $retry++;
} while ($retry < 1);

The code runs once, even if the condition is wrong in the beginning. Output:

Attempt 0

Use A do...while Loop when you want the code to run at least once. It is understood when the condition must be the first step before examining.

Here is an example:

You want to show the menu to the user at least once. Then you keep showing it until they choose to get out.

do {
  $option = showMenuAndGetChoice();
} while ($option != "exit");

The menu appears once, it doesn’t matter. If the user immediately. If you type “get out”, the loop stops after a run.

Let’s move toward the following part to take a look at the most common loop of PHP, which is for the loop.

for Loop in pHP

for The loop works when you know how often you want to drive the loop. This gives you a clear way to set the counter, test the condition and update the counter. This makes the loop easier to read and control.

There are three parts inside the loop’s bracket:

1. Start – It sets the loop. You usually describe the counter here, such as $i = 0.

2. Circumstances – Loop runs while this part is true. As soon as it goes wrong, the loop stops.

3. Step – It updates the counter after each loop runs. You can increase or reduce the price here.

Here is the structure:

for (start; condition; step) {
  // code block
}

Here is an example:

for ($i = 1; $i <= 3; $i++) {
  echo "Number: $i\n";
}

This is what happens:

• $i = 1 The initial price fixes.

• Circumstances $i <= 3 Check if the loop should walk.

• If the situation is true, the code inside runs.

• Again $i++ Increases the counter by 1.

• Loop repeats by the time $i It gets more than 3.

Output it is:

Number: 1
Number: 2
Number: 3

Here is another example:

for ($i = 2; $i <= 6; $i += 2) {
  echo "$i is even\n";
}

Here is the step $i += 2Not just $i++. It increases by 2 $i After every run instead of 1. Therefore, values ​​go from 2 to 4 to 6. Similarly you control the speed of the loop.

Output it is:

2 is even
4 is even
6 is even

You use A for Loop when:

• You know exactly how often you need to run the code

• You are working with a counter that grows or decreases

• You are going through a range, as if the number 1 to 10

• You want to keep all loop setups in one place

In the following section, you will learn about another loop called foreach. Let’s go ahead.

foreach Loop in pHP

PHP’s prediction Loop is designed to work with rows. It allows you to move through everything in the row at a time. You don’t need the counter, and you don’t need to test the size – PHP handles this section for you.

There are two ways to use foreachAnd both work only with rows or items that work like rows:

• Loop through values ​​only

• Loop through keys and values

Let’s see everyone.

Loop through values ​​only: This version gives you a value from the row on each run:

$colors = ('red', 'green', 'blue');

foreach ($colors as $color) {
  echo "$color\n";
}

Here, there are three values ​​of array. The loop gives you one at a time. You don’t get a position or index – just value.

Output here:

red  
green  
blue

Loop through keys and values: This version gives you both the key and value of each array item.

Here is an example:

$person = ('name' => 'Alice', 'age' => 30, 'city' => 'Cape Town');

foreach ($person as $key => $value) {
  echo "$key: $value\n";
}

Here, $key Every index or name holds, and $value Holds what is safe in this key.

Output it is:

name: Alice  
age: 30  
city: Cape Town

This format helps when you want to label the data, work with both the name and the value, or make something like a form or report.

Remember. foreach Only works with altitis or items that act like rows (as implementing items Traversable) You can’t use it with a simple wire or number.

If you try this:

foreach (123 as $item) {
  echo $item;
}

You have a mistake. PHP expects something that contains multiple items, such as a array or a worthy item.

You can get out of the loop break A statement based on a state or expression. Let’s move towards the next part to see how we can do it.

How to use break Described in pHP

Discovery In PHP immediately the loop ends, even if its condition is correct. His syntax is:

break;

Here is an example:

for ($i = 1; $i <= 5; $i++) {
  if ($i === 3) {
    break;
  }
  echo "$i\n";
}

When this loop stops $i 3. Output:

1
2

This PHP code uses one for Loop to count from 1 to 5. This includes a condition that stops the loop quickly break. Unless $i Equally 3, the loop ends.

Otherwise, it printed the price $i. The output is 1 and 2, and the loop goes out before reaching 3.

There are some common reasons to use break Statement:

• When you get the item you need

• If you want to get out on a particular situation

• A menu or user inside the input loop

• I switch Statements

PHP will run all code after the first match if you don’t use break. This can cause insects.

In the next section, you will see how to leave some parts of the loop when certain conditions are correct.

How to use continue Description

PHP’s issued statement Leaves the rest of the loop for the current stage. His syntax is:

continue;

Here is an example:

for ($i = 1; $i <= 4; $i++) {
  if ($i === 2) {
    continue;
  }
  echo "$i\n";
}

It does not print a loop 2 and moves to the next price. Output:

1
3
4

So, Why would you leave a part of a loop? continue?

You use continue Speaking in PHP when you want to leave the rest of the current loop block and move to the next item. This helps when you need to avoid some steps in a loop based on a condition.

You can use continue A foreachFor, for, for,. forOr while If a loop is not a price you need, you leave it and move on. You don’t stop the loop – you just leave the current run.

So why do you want to avoid a loop in some cases?

Loops give you full control, but they can lead to clutter. You repeat the same logic again and again. This makes it difficult to read the code. If you forget to update the counter or break the right time, you are also at risk of insects.

If you want to apply a process in one array, the loop may feel a lot. You do not need full control – just a clean way to make a map of values. A built -in function at the same place array_map More meaningful.

In the following section, you will see how array_map When you want a way to change everything in a row, a loop replaces.

How to change the loop array_map() In pHP

PHP’s array_ map The function helps you avoid repeated loops. It applies a callback function on each item in one or more rows and returns a new row with results.

$numbers = (1, 2, 3, 4);
$doubled = array_map(fn($n) => $n * 2, $numbers);
print_r($doubled);

Output:

(2, 4, 6, 8)

It does the same thing as one foreach Loops where you multiply each number by 2 and store the result. But with array_mapLogic lives in one place.

You pass the function and array as arguments. People mean “functional style”-you use built-in tools that focus on input and output, not stages or counters.

You get the same result, but the code for reading is less. Since then you also avoid side effects array_map Return a new row without changing the origin.

In the following section, you will understand how the nests work.

How do nest loops work in PHP

The nest loop means that one loop sits inside the other. The outer loop controls the large cycle, while the internal loop runs completely every time the outer loop once runs.

So if the outer loop runs twice and the inner loop runs three times in each cycle, the inner loop runs six times a total.

For example:

for ($i = 1; $i <= 2; $i++) {
  for ($j = 1; $j <= 3; $j++) {
    echo "i=$i, j=$j\n";
  }
}

How does it work:

• Uses an outer loop $i. It starts from 1 and runs at this time $i <= 2.

• This means that the outer loop runs twice: for once $i = 1 And for once $i = 2.

• Inside it, the inner loop uses $j. It starts from 1 and runs at this time $j <= 3.

• So each time the outer loop moves, the inner loop runs three times: for $j = 1For, for, for,. $j = 2And $j = 3.

Output:

i=1, j=1
i=1, j=2
i=1, j=3
i=2, j=1
i=2, j=2
i=2, j=3

So, How do you use a nest loop with rows?

You can also use the Nisd Loop to read the two -dimensional row. Here’s an example using the matrix:

$matrix = (
  (1, 2),
  (3, 4)
);

foreach ($matrix as $row) {
  foreach ($row as $cell) {
    echo "$cell ";
  }
  echo "\n";
}

In this case:

• External foreach The matrix gives each row.

• Every one $row There is a row: First (1, 2)Then (3, 4).

• Interior foreach Goes through all the value inside the row.

So the output it is:

1 2
3 4

You can use a nasid loop when you need to handle a grid or matrix. It also works when you want to group values.

When should you use a nest loop, and when should you not?

You may have:

• Rows and columns in the matrix

• A list of orders, with each item

• Category, with each sub -category

Whenever you have to work through a group that is sitting inside another group, nests help. They allow you to step from both levels.

For example, if you have a type of product -grown product, you can use external loop and internal loops for each product inside.

But the domestic loop also has limits. If the two loops walk several times, your code slows down. A loop inside a loop means that total steps grow rapidly.

If the outer loop runs 100 times and the internal loop runs 100 times, it takes 10,000 steps. This can cause long load times or the server can be frozen with large data sets.

The nest loops solve the real problems, but just make sure you use them only when they fit. Not everything needs anyone. If you can solve the same problem with a loop and clear data, it is often better.

Wrap

Loops help you to repeat tasks in PHP. You can use your needs, or even during predictions. Use brakes to stop quickly. Continue to leave the steps. If you work with a grid or group data, use the nasid loop.

Now hope you will understand how everyone Php loop These examples work based on clear matters of use.