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# Sorting Multidimensional Arrays by Value in PHP

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## Introduction

Sorting multidimensional arrays is a common task in PHP programming, especially when dealing with complex data structures. In this article, we will explore how to sort a multidimensional array based on a specific key within its inner arrays. Weâ€™ll demonstrate the process using a simple example and explain the steps involved in achieving the desired sorting.

## Example Scenario

Consider a multidimensional array that contains elements, each consisting of a â€˜positionâ€™ value. Our objective is to sort this array in ascending order based on the â€˜positionâ€™ value.

```\$array = [
['position' => 5],
['position' => 3],
['position' => 4],
];```

## Sorting Algorithm

To accomplish the task of sorting the multidimensional array, we need to define a custom comparison function and then use PHPâ€™s `usort()` function, which sorts an array using a user-defined comparison function.

### 1. Define a Custom Comparison Function

The first step is to create a function that will compare the â€˜positionâ€™ values of two elements in the array. The custom comparison function will return a negative value if the first elementâ€™s â€˜positionâ€™ is smaller than the second elementâ€™s â€˜positionâ€™, a positive value if the first elementâ€™s â€˜positionâ€™ is greater, and zero if both â€˜positionâ€™ values are equal.

```function sortByPosition(\$a, \$b) {
return \$a['position'] - \$b['position'];
}```

### 2. Use `usort()` with the Custom Comparison Function

Once the custom comparison function is defined, we can utilize the `usort()` function to sort the array based on the â€˜positionâ€™ value. The `usort()` function will take the array to be sorted as the first argument and the name of the custom comparison function as the second argument.

`usort(\$array, 'sortByPosition');`

## Final Output

After sorting the array using the `usort()` function, we can print the result to verify the sorting order.

`print_r(\$array);`

The output will be:

```Array
(
[0] => Array
(
[position] => 3
)

[1] => Array
(
[position] => 4
)

[2] => Array
(
[position] => 5
)
)```

## Conclusion

Sorting multidimensional arrays in PHP can be achieved by defining a custom comparison function and then using the `usort()` function. This process allows us to sort the array based on specific keys within its inner arrays, providing a versatile way to organize complex data structures in our PHP applications.

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