How to determine if an array is empty in php

In PHP, there are many ways to determine whether an array is empty. This article will introduce several common methods:

1. empty() function

empty() function is a function used in PHP to determine whether a variable is empty. It is suitable for All variable types.

The following is a sample code that uses the empty() function to determine whether the array is empty:

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

In the above code, we assign an empty array to the variable $arr, and then use empty () function to determine whether the array is empty. When the parameter of the empty() function is an empty array, the return value is true, otherwise it returns false.

2. count() function

The count() function in PHP can be used to get the number of elements in an array. For an empty array, the return value is 0. Therefore, we can use the count() function to determine whether an array is empty.

The following is a sample code that uses the count() function to determine whether the array is empty:

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

In the above code, we use the count() function to get the number of array elements, and Determine whether it is equal to 0 to determine whether the array is empty.

3. isset() function

isset() function is used to determine whether a variable has been declared and assigned a value, and is applicable to all variable types. When an array has no elements, you can use the isset() function to determine whether the array is empty.

The following is a sample code that uses the isset() function to determine whether the array is empty:

$arr = array();
if (isset($arr) && empty($arr)) {
    echo '数组为空';
} else {
    echo '数组不为空';
}

In the above code, we first use the isset() function to determine whether the variable has been declared and assigned a value. , and then use the empty() function to determine whether the array is empty.

4. array() type detection

In PHP, the array() type can be used to determine whether a variable is an array type. For an empty array, we can use array() to determine whether the array is empty.

The following is a sample code that uses array() type detection to determine whether the array is empty:

$arr = array();
if (is_array($arr) && count($arr) == 0) {
    echo '数组为空';
} else {
    echo '数组不为空';
}

In the above code, we first use the is_array() function to determine whether the variable is an array type. , and then use the count() function to determine whether the array is empty.

5. foreach loop detection

The foreach loop can be used to traverse all elements in an array. When an array has no elements, the foreach loop will not perform any operation, so You can use this to determine whether an array is empty.

The following is a sample code that uses a foreach loop to detect whether the array is empty:

$arr = array();
$isEmpty = true;
foreach ($arr as $val) {
    $isEmpty = false;
    break;
}
if ($isEmpty) {
    echo '数组为空';
} else {
    echo '数组不为空';
}

In the above code, we first define a variable $isEmpty and set its initial value to true. Then use a foreach loop to traverse the elements in the array. When the loop body is executed once, set the value of $isEmpty to false, and use the break statement to jump out of the loop.

Finally use the IF statement to determine the value of $isEmpty to determine whether the array is empty.

Summary:

In PHP, there are many ways to determine whether an array is empty, including empty() function, count() function, isset() function, array() type detection And foreach loop detection, etc. Depending on the specific scenario and needs, you can choose different methods to determine whether the array is empty.

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