Doesn't php have real arrays?

PHP is a commonly used web programming language, which can be used to implement various dynamic web pages and web applications. For programmers using PHP, arrays are one of the most basic and useful data types in the language. However, in PHP, arrays are not really arrays, which this article will explore in detail.

Characteristics of PHP arrays

In PHP, arrays are a very flexible data type that can store any type of value. In PHP, arrays can be declared and defined in two ways:

$arr1 = array('a', 'b', 'c');
$arr2 = ['a', 'b', 'c'];

As you can see, unlike other programming languages, in PHP, you can use array or square brackets to declare array.

The detailed information of the array can be printed through the var_dump() function:

$arr = ['a', 'b', 'c'];
var_dump($arr);

The output result is:

array(3) {
  [0]=>
  string(1) "a"
  [1]=>
  string(1) "b"
  [2]=>
  string(1) "c"
}

As you can see, this is an array containing An array of three elements, each element being of type string. In addition, arrays in PHP also allow the use of associative arrays, that is, you can use strings as subscripts.

$assoc_arr = [
    'name' => 'John',
    'age' => 25,
    'gender' => 'male'
];
var_dump($assoc_arr);

The output result is:

array(3) {
  ["name"]=>
  string(4) "John"
  ["age"]=>
  int(25)
  ["gender"]=>
  string(4) "male"
}

As you can see, this is an associative array containing three elements.

Defects of PHP arrays

Although arrays in PHP look very convenient, they actually have some flaws.

First of all, arrays in PHP are actually hash tables (Hash Table), which means that the subscripts of the array are actually string types, not integers. This is different from most programming languages, such as C, Java and Python, where arrays are based on integer subscripts.

Secondly, since arrays in PHP are actually hash tables, it is not efficient at processing large arrays. When dealing with large arrays, PHP's memory consumption and runtime can be significant.

In addition, the array in PHP is actually a composite data type, which contains two data types: key-value pairs and ordered lists, which makes its underlying implementation more complex and stores array elements internally. The memory required is also higher than other languages.

Finally, you need to pay attention when using arrays in PHP, because it is a weakly typed data type, so in some cases problems such as type conversion errors may occur, which requires programmers to perform additional inspection and processing.

Optimization of PHP arrays

In view of the above defects of PHP arrays, in order to improve the efficiency of PHP arrays, programmers can take the following optimization measures:

• Use as much as possible Integers are used as array subscripts to reduce the use of string types, which can improve the speed of array access.
• For processing large arrays, you can consider using other data structures, such as trees and hash tables, to optimize access efficiency.
• For arrays that require quick sorting and binary search, they can be converted into standard arrays, which can improve access efficiency.
• Use the native array type in PHP 7, which is more efficient when dealing with large arrays.

In addition, programmers can also use caching and other technologies to improve the access speed and processing efficiency of PHP arrays.

Conclusion

To sum up, although the PHP array is not a real array, but a hash table, it is still one of the most commonly used and practical data types in PHP. It is very important for programmers to understand the characteristics and pitfalls of PHP arrays. Optimizing the use and efficiency of PHP arrays is also one of the skills that every PHP programmer must master.

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