update

I'm new to PHP development: I looked on the PHP website for a function - array_slice. I read and looked at the example but I don't understand it. Can someone explain this in clear words for me?

I think it works as follow?

$example = array(1,2,3,4,5,6,7,8,9);
$offset = 2;
$length = 5;
$newArray = array_slice($example, offset, length);

the result of $newArray is: 开发者_如何学C$newArray(3,4,5,6,7);

In addition to stefgosselin's answer that has some mistakes: Lets start with his array:

$input = array(1,2,3);

This contains:

array(3) {
    [0]=> int(1)
    [1]=> int(2)
    [2]=> int(3)
}

Then you do array_slice:

var_dump(array_slice($input, 1));

The function will return the values after the first element (thats what the second argument, the offset means). But notice the keys!

array(2) {
    [0]=> int(2)
    [1]=> int(3)
}

Keep in mind that keys aren't preserved, until you pass true for the fourth preserve_keys parameter. Also because there is another length parameter before this, you have to pass NULL if you want to return everything after the offset, but with the keys preserved.

var_dump(array_slice($input, 1, NULL, true));

That will return what stefgosselin (incorrectly) wrote initially.

array(2) {
    [1]=> int(2)
    [2]=> int(3)
}

This function returns a subset of the array. To understand the example on the man page you have to understand array keys start at 0, ie

 $array_slice = $array(1,2,3);

The above contains this:

$array[0] = 1,
$array[1] = 2,
$array[2] = 3

So, array_slice(1) of $array_sliced would return:

$arraysliced = array_slice($array_slice, 1);
$arraysliced[1] = 2;
$arraysliced[2] = 3; 

It returns the part of your input array that starts at your defined offset, of the your defined length.

Think of it this way:

$output = array();
for ($i = 0; $i++; $i < count($input)) {
  if ($i < $start)
    continue;
  if ($i > $start + $length)
    break;
  $output[] = $input[$i];
}

Basically its an skip and take operation. Skip meaning to jump to that element. Take meaning how many.

PHP has a built - in function, array_slice() , that you can use to extract a range of elements from an array. To use it, pass it the array to extract the slice from, followed by the position of the first element in the range (counting from zero), followed by the number of elements to extract. The function returns a new array containing copies of the elements you extracted (it doesn ’ t touch the original array). For example:

$authors = array( “Steinbeck”,
“Kafka”, “Tolkien”, “Dickens” );
$authorsSlice = array_slice(
$authors, 1, 2 ); // Displays “Array
( [0] = > Kafka [1] = > Tolkien )”
print_r( $authorsSlice );

By the way, if you leave out the third argument to array_slice() , the function extracts all elements from the start position to the end of the array:

$authors = array( “Steinbeck”, “Kafka”, “Tolkien”, “Dickens” );
$authorsSlice = array_slice( $authors, 1 );
// Displays “Array ( [0] = > Kafka [1] = > Tolkien [2] = > Dickens )”;
print_r( $authorsSlice );

Earlier you learned that array_slice() doesn ’ t preserve the indices of elements taken from an indexed array. If you want to preserve the indices, you can pass a fourth argument, true , to array_slice() :

$authors = array( “Steinbeck”, “Kafka”, “Tolkien”, “Dickens” );
// Displays “Array ( [0] = > Tolkien [1] = > Dickens )”;
print_r( array_slice( $authors, 2, 2 ) );
// Displays “Array ( [2] = > Tolkien [3] = > Dickens )”;
print_r( array_slice( $authors, 2, 2, true ) );