array_slice is a built-in function in PHP that is used to extract a portion of an array and return it as a new array. It takes three main parameters:

1. Input Array: The original array from which you want to extract a portion.

2. Start Index: The index at which the extraction should begin.

3. Length (optional): The length of the extracted portion. If omitted, the slice will extend to the end of the array.

Here is the basic syntax of array_slice :

array_slice(array, start, length, preserve_keys);

• array: The original array.
• start: The index to start the slice from. If this is a positive number, the slice will start at that index in the array. If it's negative, the slice will start that many elements from the end of the array.
• length: (Optional) The length of the slice. If omitted, the slice will include all elements from the start index to the end of the array.
• preserve_keys: (Optional) A boolean flag (true/false) indicating whether to preserve the keys or not. If set to true, the resulting array will have the same keys as the original. If set to false (default), the keys will be re-indexed.

 
$students = ['John', 'Jane', 'Doe', 'Alice', 'Bob'];
 
$sliced_students = array_slice($students, 1, 2);
 
// Result: ['Jane', 'Doe']
 

1. The function array_slice takes the students array and starts the slice from index 1 (which is the second element, 'Jane').
2. It then extracts 2 elements, resulting in ['Jane', 'Doe'].

 
$students = ['John', 'Jane', 'Doe', 'Alice', 'Bob'];
 
$sliced_students = array_slice($students, -2);
 
 
// Result: ['Alice', 'Bob']
 
 

1. In this example, the function starts from the second-to-last element (-2 indicates the second-to-last index).
2. It extracts all elements from that index to the end of the array, resulting in ['Alice', 'Bob'].

 
$students = ['John', 'Jane', 'Doe', 'Alice', 'Bob'];
 
$sliced_students = array_slice($students, 1, -1);
 
 
// Result: ['Jane', 'Doe', 'Alice']
 
 

1. The third parameter -1 indicates that the slice should go up to the second-to-last element.
2. So, it extracts elements from index 1 to the second-to-last element, resulting in ['Jane', 'Doe', 'Alice'].

 
$products = [
    'apple' => 2,
    'banana' => 1,
    'cherry' => 3,
    'date' => 4
];
 
$sliced_products = array_slice($products, 1, 2, true);
 
 
// Result: ['banana' => 1, 'cherry' => 3]
 

1. Here, the input array is associative, meaning it has keys ('apple', 'banana', etc.) associated with values (2, 1, etc.).
2. The function works the same way, but preserves the keys. So, it extracts the elements starting from the second key, resulting in ['banana' => 1, 'cherry' => 3].

In summary, array_slice is a versatile function that allows you to extract a portion of an array based on specified parameters. It can be used with both indexed and associative arrays. It's essential to understand how indices work in PHP arrays to use this function effectively.