How to fill arrays in different ways in PHP?

In the previous article "Take you to quickly master the replacement of array elements in PHP (detailed examples)", we introduced the relevant knowledge of how to replace array elements in PHP in detail. Let's take a look at this article. Let’s take a look at the relevant knowledge about filling arrays in PHP array operations. I hope it will be helpful to everyone!

In the previous article, we learned that if you want to replace elements in an array, you can use the array_splice function, array_replace function and array_replace_recursive function to achieve. Next, let's take a look at how to implement the filling operation of arrays in PHP.

In PHP, if you want to fill an array, you can use the array_fill function and the array_fill_keys function. Let’s take a look at these two functions separately. How to use.

<strong><span style="font-size: 20px;">array_fill</span></strong>Function - key value fill array

In In PHP, you can fill an array with key values ​​through the array_fill function. The basic syntax format of the array_fill function is as follows:

array_fill(index,number,value);

What you need to pay attention to is: these three Both parameters are required. Parameter index represents the first index in the returned array. Parameter number represents the number of elements to be inserted. Parameter value represents the value used for filling.

If the parameter index is a positive number, the index in the returned array will start from the parameter index; if the parameter index is a negative number, then the index in the returned array will be returned Only the index of the first element in the array is the parameter index, the second is 0, the third is 1 and so on.

There are a total of parameter number elements in the returned array, and the filled value is value, if the parameter number is 0# If ## or less than 0, the function will be wrong. The function runs successfully and the returned result is the filled array.

Let’s take a look at the application of the

array_fill function through an example. The example is as follows:

<?php
$a1=array_fill(3,4,"blue");
print_r($a1);
?>

Output result:

Let’s take a look at what happens to the result when the parameter

index is negative. The example is as follows:

<?php
$a1=array_fill(3,4,"blue");
print_r($a1);
echo &#39;<br/>&#39;;
$a2=array_fill(-3,4,"blue");
print_r($a2);
?>

Output result:

The above example shows the change in the output result if the parameters

index are different, that is, the change in the index.

<strong>array_fill_keys<span style="max-width:90%"></span></strong>Function - Fill array with keys and values

In PHP, we can use the

array_fill_keys function to fill the array with keys and values. The basic syntax format of the array_fill_keys function is as follows:

array_fill_keys(keys,value);

What needs to be noted is: Both parameters are required. Parameter

keys means using the array value of this parameter as the key of the new array. If the value in parameter keys is not standardized, it will be converted. It is a string, and the parameter value represents the value used to fill the array. The result returned is a filled array.

Let’s take a look at the application of the

array_fill_keys function through an example. The example is as follows:

<?php
$keys=array("a","b","c","d");
$a1=array_fill_keys($keys,"blue");
print_r($a1);
?>

Output result:

In the above example, the parameter value has only one value. At this time, all the filled arrays have one value. When there is more than one parameter value, the example is as follows:

<?php
$keys=array("a","b","c","d");
$a1=array_fill_keys($keys,"blue");
print_r($a1);
echo &#39;<br/>&#39;;
$value=array(&#39;red&#39;,&#39;green&#39;,&#39;blue&#39;);
$a2=array_fill_keys($keys,$value);
echo "<pre class="brush:php;toolbar:false">";
var_dump($a2);
?>

Output Result:

#In the above example, when the parameter value is also an array, the output result will become a multi-dimensional array.

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