Array_slice() doesn't work as expected on nested arrays

Question

So, I was designing a function that can take multiple arguments via the spread operator (...$arg)

but it can also take a simple input array. I want to access the first element of the array with the array_slice() method, but it doesn't work as expected:

    // This is what the spread argument passes into the function if it gets a single array
    $arg = [
      ['value1', 'value2', 'valueN'],  
    ];

    // Accessing first element via array_slice:
    var_export( array_slice($arg, 0, 1) );

Expected result:

     array (
       0 => 'value1',
       1 => 'value2',
       2 => 'valueN',
     )

The result is basically equal to the input array:

    array (
      0 => 
      array (
        0 => 'value1',
        1 => 'value2',
        2 => 'valueN',
      ),
    )

I know I can just simply access the 0th element ($arg[0]) to get the first item, but I'm curious why array_slice() doesn't work as I would expect. What am I missing here?

Vaibhav Gidde · Accepted Answer · 2020-02-25 12:07:14Z

2

You are expecting the first value from your array. array_slice return the sliced array. You can use array_shift instead which will shifts the first value of the array off and returns it.

print_r(array_shift($arg));

Output:

array (
       0 => 'value1',
       1 => 'value2',
       2 => 'valueN',
     )

answered Feb 25, 2020 at 12:07

Vaibhav Gidde

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1 Comment

Gergely Lukacsy Over a year ago

Thanks! Using current($arg) also does the job.

Alexandre Elshobokshy · Accepted Answer · 2020-02-25 11:47:44Z

1

It's working as expected. It's returning the first element of your $arg array, which is the array with the key 0 containing an array by itself and not the contents of the first element. You're just misunderstanding how array_slice actually works.

array (
  0 => 
  array (
    0 => 'value1',
    1 => 'value2',
    2 => 'valueN',
  ),
)

edited Feb 25, 2020 at 11:47

answered Feb 25, 2020 at 11:39

Alexandre Elshobokshy

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1 Comment

Gergely Lukacsy Over a year ago

Ah, I get it now, it always returns an array. I don't know what I was thinking... thanks for the answer

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