PHP loops cheat sheet

This cheat sheet provides a quick reference guide for various types of loops in PHP. Loops are essential for executing a block of code repeatedly, allowing for efficient and streamlined programming. The following sections outline the syntax and provide examples for each type of loop, along with the usage of break and continue statements.

For loop

The for loop is ised to execute a block of code a specific number of times.

Syntax

for (initialization; condition; increment/decrement) {
    // Code to be executed
}   

Example

for ($i = 0; $i < 5; $i++) {
    echo "The number is: $i <br>";
}

Output

The number is: 0
The number is: 1
The number is: 2
The number is: 3
The number is: 4

While loop

The while loop executes a block of code as long as the specified condition is true.

Syntax

while (condition) {
    // Code to be executed
    // Increment or decrement variable inside the loop if necessary
}     

Example

$i = 0;

while ($i < 5) {
    echo "The number is: $i <br>";
    $i++;
}

Output

The number is: 0
The number is: 1
The number is: 2
The number is: 3
The number is: 4

Do-While loop

The do-while loop is similar to the while loop, but the code is executed at least once before the condition is checked.

Syntax

do {
    // Code to be executed
    // Increment or decrement variable inside the loop if necessary
    } while (condition);      

Example

$i = 0;

do {
    echo "The number is: $i <br>";
    $i++;
    } while ($i < 5);

Output

The number is: 0
The number is: 1
The number is: 2
The number is: 3
The number is: 4

Foreach loop (for arrays)

The foreach loop (for arrays) iterates through each element in an array.

Syntax

foreach ($array as $value) {
    // Code to be executed
}

Example

$colors = array("Red", "Green", "Blue");

foreach ($colors as $value) {
    echo "$value <br>";
}

Output

Red
Green
Blue

Foreach loop (for associative arrays)

The foreach loop (for associative arrays) Iterates through each element in an associative array, providing both the key and the value.

Syntax

foreach ($array as $key => $value) {
    // Code to be executed
}

Example

$age = array("Peter" => "35", "Ben" => "37", "Joe" => "43");

foreach ($age as $key => $value) {
    echo "$key is $value years old <br>";
}

Output

Peter is 35 years old
Ben is 37 years old
Joe is 43 years old

Break statement

The break statement terminates the loop when a specified condition is met.

Syntax

Syntax example using a for loop and if statement.

for (initialization; condition; increment/decrement) {
    if (condition) { 
    break; // Terminate the loop
    }
}

Example

In this example, the for loop will terminate when the variable ‘i’ reaches 3.

for ($i = 0; $i < 5; $i++) {
    if ($i == 3) {
       break; // Terminate the loop
    }
    echo "The number is: $i <br>";
}

Output

The number is: 0
The number is: 1
The number is: 2

Continue statement

The continue statement skips the current iteration of a loop based on a specific condition.

Syntax

Syntax example using a for loop and if statement.

for (initialization; condition; increment/decrement) {
    if (condition) {
        continue; // Skip this iteration
    }
    // Code to be executed
}

Example

This example will output the numbers from 0 to 4, skipping the number 3.

for ($i = 0; $i < 5; $i++) {
    if ($i == 3) {
        continue; // Skip this iteration
    }
    echo "The number is: $i <br>";
}

Output

The number is: 0 
The number is: 1 
The number is: 2
The number is: 4