How php detects the existence of array key

This article focuses on "how to detect the existence of array key by php". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "php how to detect the existence of array key"!

Two methods: 1. Use "array_key_exists (" specify key value ", $arr)", and return true if it exists. 2. Use "isset ($arr [" specify key value "]" to detect whether the value corresponding to the specified key name exists, and then determine whether key exists, and return true if it exists.

Operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

There are two ways for php to detect the existence of array key:

1. Use the array_key_exists () function

The array_key_exists () function checks whether the specified key name exists in an array, returns true if the key name exists, and false if the key name does not exist.

2. Use the isset () function

The isset () function is used to detect whether the variable is set and is not NULL.

Detection ideas:

Access the specified array elements using the array name ["key"]

Use the isset () function to detect the existence of the array element

Returns TRUE if it exists and is not NULL, otherwise returns FALSE.

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