The PHP loops are iterative control structures that execute the same block again and again till a specific condition is satisfied.
Read Also: PHP Switch and Continue
Loops in PHP
This article shows how to use the different loops in PHP. Loops are a key way to control the execution of code.
Like loops in other programming languages, a loop in PHP is useful to execute a statement or a block of statements multiple times until some condition becomes true. It helps the user to save both time and effort to repeatedly write the same lines of code.
PHP supports four different types of loops:
- For loop
- While loop
- Do while loop
- Foreach loop
Let us see the detailed description of each loop mentioned in the list.
For Loop
For loop is useful when the user knows how many times the block needs to be executed. The for loop repeats a particular block of code as long as a specific condition is satisfied. It consists of three parameters, namely initialization, test condition, and the counter.
Syntax
for(initialization; condition; increment){
//code to be executed
}First, initialize the loop variable to some value, then check whether the variable is less than or greater than the counter value. If the statement is true loop body is executed, and loop variables get updated. Steps are repeated till the exit condition is reached.
- Initialization: In this expression, we must initialize the loop variable to some value.
- Condition: At the starting of each iteration, the condition is evaluated. If it evaluates to true, the loop continues, and if it evaluates to false, the execution of the loop ends.
- Increment: It updates the loop counter with a new value.
How for loop in PHP works
Example
<?php
for($i = 1; $i <= 13; $i++){
echo “The number id”.$i.”<br>”;
}
?>Output
The number id1 The number id2 The number id3 The number id4 The number id5 The number id6 The number id7 The number id8 The number id9 The number id10 The number id11 The number id12 The number id13
While Loop
The While loop iterates a block of code until some condition becomes true. It is an entry control loop. The loop first checks the condition at the starting of the loop, then if it is true, it executes the block of statements and goes on executing until some condition becomes true. The while loop is useful to read records returned from a database query.
Syntax
While(if the condition is true){
//Code to be executed
}How while loop works in PHP
Example
<?php
$num = 2;
while ($num < 12) {
$num += 2;
echo $num, "\n";
}
?>Output
4 6 8 10 12
Do While Loop
The do-while loop is a variant of a while loop. It is an exit control loop. The do-while loop first enters the loop executes the statements and then checks the condition. A statement executes at least once on using the do-while loop. After executing once, the program executes as long as the condition holds.
Syntax
do{
//code to be executed
}While(if condition is true);How Do while works in PHP
Example
<?php
$num = 2;
do {
$num += 2;
echo $num, "\n";
} while ($num < 12);
?>Output
4 6 8 10 12Difference between while and do-while loop
| While loop | Do-while loop |
| In a while loop, the controlling condition appears at the start of the loop. | In the do-while loop, the controlling condition appears at the end of the loop. |
| The loop never executes if the condition at the first iteration appears false. | At least once the loop executes, even if the condition is false at the first iteration. |
| The while is also known as entry controlled loop. | The do-while is also known as an exit controlled loop. |
| In the while loop, the semicolon is not used. | In the do-while loop, a semicolon is used at the end of the loop. |
For each loop
The for-each loop is useful to loop over arrays. Please read our article on the PHP foreach loop for detailed information.
Syntax
foreach(array_element as value){
//code to be executed
}There is one more syntax for each loop which is the extension of the first
foreach($array as $key => $value){
//code to be executed
}Example 1
<?php $colors = array(“Red”,”Green”,”Blue”); foreach ($colors as $value) { echo "$value<br>"; } ?>
Output
“Red” ”Green” ”Blue”
Example 2
<?php $superhero = array ( "name" => "Suman", "email" => "[email protected]", "age" => "18" ); foreach($superhero as $key => $value){ echo $key ." : " .$value ."<br>"; } ?>
Output
name: Suman email: [email protected] age:18
Read More: PHP Functions
Conclusion
PHP loops are often used while programming web applications. They are really useful for reducing time and minimizing errors. If you are still unclear about some of the other basic concepts of PHP programming, you can read through our previous blogs. Happy Learning!
