php array subscript conversion

In PHP, we often use arrays to store some data. Array subscripts can affect the performance of arrays and the efficiency of operations to a certain extent. When improving program performance, we often need to convert array subscripts. This article will introduce the methods and steps of array subscript conversion in PHP.

1. Why array subscript conversion is needed

In PHP, array is a common data type. It can be used to store large amounts of data and process and operate on this data. However, if the type and number of subscripts in the array are inappropriate, the performance and efficiency of the program may be affected. For example, when the subscript is a string type, using an index to access the array will cause PHP to perform hash calculations internally, thus slowing down the program. At this time, we need to convert the array subscript to optimize program performance.

2. Array subscript conversion method

In PHP, we can convert array subscripts in a variety of ways, including:

1. Convert a string Subscripts are converted to integer subscripts:

Prior to PHP 5.4, it was very common to access arrays using arrays of string subscripts. However, after PHP 5.4, accessing arrays using numeric subscript arrays is faster and more efficient than accessing arrays using string subscript arrays. Therefore, we can convert string subscripts to integer subscripts to optimize program performance.

Sample code:

$arr = array(
    'a' => 1,
    'b' => 2,
    'c' => 3,
);

$arr = array_values($arr); //将字符串下标转换为整数下标

print_r($arr);

2. Convert a large number of string subscripts to a constant or enumeration type:

In PHP, a large number of characters String constants may affect program performance and operating efficiency. We can convert these string constants into constant or enumeration types, thus improving the performance of the program.

Sample code:

const USER_NAME = 'uname';
const USER_EMAIL = 'uemail';
const USER_PHONE = 'uphone';

$userData = array(
    USER_NAME => '张三',
    USER_EMAIL => 'zhangsan@test.com',
    USER_PHONE => '13100000000',
);

print_r($userData);

3. Use array functions to convert string subscripts:

PHP provides a series of array functions that can String subscripts are converted. Commonly used functions include array_keys() and array_values(). The array_keys() function can get all the key names of the array, and the array_values() function can get all the values ​​of the array. We can use these two functions together to convert array subscripts.

Sample code:

$arr = array(
    'a' => 1,
    'b' => 2,
    'c' => 3,
);

$newKeys = array_keys($arr);
$newValues = array_values($arr);

$newArr = array_combine($newKeys, $newValues); //使用array_combine()函数合并键名和键值

print_r($newArr);

In the above example, the array_keys() and array_values() functions are used to obtain the key name and key value of the original array respectively. Then, use the array_combine() function to combine the new key names and key values ​​to generate a new array $newArr.

3. Summary

Array subscript conversion is one of the important techniques for optimizing the performance of PHP programs. By properly using conversion techniques, we can make PHP programs more efficient, faster, and smoother. In actual programming work, it is necessary to select an appropriate subscript conversion method based on the actual situation to achieve the effect of optimizing program performance.

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