PHP Loop: automatic repetition of program sequences

PHP Loops reduce the development period considerably, as they allow repetitive tasks to be automated. There flexibility offered by these loops allows you to customize the number of repetitions or set a reaction based on certain conditions.

PHP Loops: what is it?¶

PHP loops are particularly useful for automate repetitive tasks, process data or browse lists or even PHP tables. This allows you to repeat the execution of a specific instruction or block of code, without having to write it multiple times. Likewise, don't hesitate to use PHP functions or PHP classes; This allows you to improve the efficiency of your PHP applications. This makes maintaining your entire program easier because you are able to organize repetitive actions within a clear structure.

What are the different types of PHP Loops?¶

There are different types of PHP loops, including:

• THE for loops : they allow you to execute an instruction a certain number of times. They include an initial expression, a condition and an increment;
• THE while loops : they execute an instruction, provided that the specified condition turns out to be “true”;
• THE do while loops : they resemble while loops, but the condition is checked once the instruction is executed. So the code is called at least once;
• THE foreach loops : in PHP, they allow you to iterate over the elements of an array or a list and apply commands to each element.

What is the syntax of PHP Loops?¶

The syntax of PHP loops depends on the type of loop used, but the basic schema always remains the same, with a condition and a block of code.

PHP Loop: for loop¶

The for loop may be suitable for you if you already know how many times the code should be repeated. Its syntax is as follows:

for (init counter; test counter; increment counter) {
  code to be iterated;
}

• init counter : this is the starting value, the one with which the loop begins. A variable is normally initialized there;
• test counter : this is the condition checked at each pass through the loop. As long as this condition remains true ( » true « ), the loop continues to execute. If the condition becomes false (“ false « ), then the loop is interrupted;
• increment counter : this is the part of the code allowing the initial value to be increased or reduced each time the loop is repeated. It can also be referred to as “increment”.

PHP Loop: while loop¶

Not sure how many times the code block should be repeated? We advise you to opt for a while loop.

while (condition is true) {
  code to be executed;
}

• condition : this is an expression condition. This is evaluated before each new iteration of the loop.

Do while loop in PHP¶

The code is executed at least once with the do while loop, regardless of the condition.

do {
  code to be executed;
} while (condition is true);

• condition : This is the expression condition checked after the first execution of the code block.

foreach loop in PHP¶

This loop can be particularly useful if you are looking to iterate through the elements of a list or a associative array (i.e. an array containing key-value pairs).

foreach ($array as $value) {
  code to be executed;
}

• $array : this is the indication of the table to be browsed or the iterable data type;
• value : this is a temporary variable which represents the value of an element of the array at each iteration of the loop.

for ($i = 1; $i <= 5; $i++) {
    echo $i . " ";
}

$i = 1;
do {
    echo $i . " ";
    $i++;
} while ($i <= 5);

$sql = "SELECT * FROM user";

$result = mysqli_query($conn, $sql);

if (!$result) {
    die("Query failed: " . mysqli_error($conn));
}

while ($row = mysqli_fetch_assoc($result)) {
    echo "username: " . $row["username"] . "<br>";
    echo "email: " . $row["email"] . "<br>";
    echo "age: " . $row["age"] . "<br>";
    echo "<hr>";
}

$fruits = ["Apple", "Banana", "Cherry", "Date", "Fig"];

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