How to determine if an array is empty in php

In PHP, it is usually necessary to perform various operations on arrays, including determining whether the array is empty. There are many methods in PHP to determine whether an array is empty. This article will introduce the use of these methods and their advantages and disadvantages.

Method 1: count() function

The count() function is one of PHP’s built-in functions, used to return the number of elements in an array. When the array is empty, the return value is 0, so you can use the count() function to determine whether the array is empty.

The following is an example of using the count() function to determine if the array is empty:

$emptyArray = array();
if (count($emptyArray) == 0) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

When the array $emptyArray is empty, the code will output "The array is empty", Otherwise it outputs "array is not empty".

Advantages:

• count() function is a built-in function of PHP, does not require any dependencies, and is relatively fast.

Disadvantages:

• It is impossible to determine whether there is false, 0 or empty string in the array, because their count() values ​​are all is 1.

Method 2: empty() function

The empty() function is one of PHP's built-in functions, used to check whether a variable is "empty". The return value is true when the variable is:

1. The variable value is false.
2. The variable is null.
3. The variable is 0 or the string "0".
4. The variable is the empty string "".
5. The variable is an empty array.

Therefore, you can use the empty() function to determine whether the array is empty.

The following is an example of using the empty() function to determine if the array is empty:

$emptyArray = array();
if (empty($emptyArray)) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

When the array $emptyArray is empty, the code will output "The array is empty", Otherwise it outputs "array is not empty".

Advantages:

• empty() function is a PHP built-in function without any dependencies.

Disadvantages:

• Cannot determine whether false, 0 or empty string exists in the array.

Method 3: is_null() function

The is_null() function is one of PHP’s built-in functions, used to determine whether a variable is null. Therefore, you can use the is_null() function to determine whether the array is null and infer whether the array is empty.

The following is an example of using the is_null() function to determine if the array is empty:

$emptyArray = array();
if (is_null($emptyArray)) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

When the array $emptyArray is empty, the code will output "The array is empty", Otherwise it outputs "array is not empty".

Advantages:

• is_null() The function is a built-in function of PHP and does not require any dependencies.

Disadvantages:

• Cannot determine whether false, 0 or empty string exists in the array.

Method 4: isset() function

isset() function is one of PHP’s built-in functions, used to check whether the variable has been set and is not null. Therefore, you can use the isset() function to determine whether the array is set and non-null, and to infer whether the array is empty.

The following is an example of using the isset() function to determine if the array is empty:

$emptyArray = array();
if (!isset($emptyArray) || empty($emptyArray)) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

When the array $emptyArray is empty, the code will output "The array is empty", Otherwise it outputs "array is not empty".

Advantages:

• isset() The function is one of PHP's built-in functions and does not require any dependencies.

Disadvantages:

• Cannot determine whether false, 0 or empty string exists in the array.

Method 5: array_key_exists() function

array_key_exists() function is one of PHP’s built-in functions, used to determine whether the specified key name exists in the array. Therefore, you can use the array_key_exists() function to determine whether the array is empty.

The following is an example of using the array_key_exists() function to determine if the array is empty:

$emptyArray = array();
if (!array_key_exists(0, $emptyArray)) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

When the array $emptyArray is empty, the code will output "The array is empty", Otherwise it outputs "array is not empty".

Advantages:

• array_key_exists() The function is one of PHP’s built-in functions and does not require any dependencies.

Disadvantages:

• Cannot determine whether false, 0 or empty string exists in the array.
• It can only determine the existence of the specified key name, but cannot determine whether the entire array is empty.

Conclusion

In PHP, there are many ways to determine whether an array is empty, and each method has its advantages and disadvantages. If you only need to determine whether there are elements in the array, using the count() function or the empty() function is a good choice. If you need to perform more processing on the values ​​in the array, or if you need to simultaneously determine whether there is false, 0, or an empty string in the array, you can use the array_filter() function or a custom function.

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