what is php enum array

The enumeration array in PHP, as the name suggests, is that a developer has predefined a series of constant arrays, and uses enumerations to represent this array, following certain specifications to make the program more readable. Maintenance is more convenient.

In PHP programming, enumeration array is a very common data structure. It can define some sets of constants and perform operations and calculations on these constants to meet business needs in the program.

In order to better understand and master enumeration arrays, we first need to understand the concepts and characteristics of enumerations.

The concept of enumeration

An enumeration is a collection of constants, which are often used to represent some constants that have a fixed meaning in the program. For example, a traffic light can be represented as a set of three constants: red, yellow, and green, or as an enumeration of three states: red, yellow, and green.

In PHP, we can use enumeration arrays to represent some constant collections.

Characteristics of enumerations

1. Limited constants: Enumerations are composed of certain constants. The value range of these constants is limited and the length is usually very short.
2. Unique constants: Each constant in the enumeration is unique, that is, there will be no duplication.
3. Constant immutability: Constants in enumerations are usually immutable. Once the definition is completed, they cannot be modified.
4. Constant Comparability: Constants in enumerations can be compared, either with numbers or with other constants.

Enumeration array in PHP

Sometimes, we need to represent a series of constant values ​​in the program, and the value range of these constants is fixed. At this point, we can usually use an enumeration array to define these constants.

In PHP, defining an enumeration array is actually defining an ordinary array, but the elements in the array are all constant values. These elements are usually represented by uppercase letters and can be strings, numbers, or other data types.

For example, we can define an enumeration array representing gender like this:

<?php
define(&#39;GENDER_MAN&#39;, 1);
define(&#39;GENDER_WOMAN&#39;, 2);
define(&#39;GENDER_UNKNOWN&#39;, 3);
?>

Here, we use the define() function to define three constant values, each constant value represents A different gender. After that, we can put these three constant values ​​into an array:

<?php
$genders = array(
    GENDER_MAN => '男',
    GENDER_WOMAN => '女',
    GENDER_UNKNOWN => '未知'
);
?>

In this way, we define an array named $genders, which contains three elements. These three elements have GENDER_MAN, GENDER_WOMAN and GENDER_UNKNOWN as key names respectively, and 'male', 'female' and 'unknown' as key values.

In actual applications, we can get or set the corresponding constant value by accessing this array. For example, if you need to get the constant value of 'male', you can do this:

<?php
$man = $genders[GENDER_MAN];
?>

Similarly, if you need to modify the constant value of 'unknown', you can also do this:

<?php
$genders[GENDER_UNKNOWN] = &#39;不详&#39;;
?>

In this way, we Enumeration arrays can be conveniently used to handle some business needs.

Summary

The enumeration array is a very common data structure and is widely used in PHP programming. It can make the program logic clearer and the code easier to read and maintain. When applying enumeration arrays, you need to pay attention to the uniqueness and immutability of constants, and also name them reasonably to make the code easier to read and avoid confusion and errors.

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