How to determine if an array is empty in php

Arrays in PHP are commonly used data types. When we operate an array, we need to determine whether the array is empty, because when the array is empty, we use array functions or operations, which will cause a series of errors and even cause the program to crash. . Therefore, when writing PHP programs, we need to pay special attention to whether the array is empty.

To determine whether a PHP array is empty, there are several methods to choose from.

Method 1: Use empty function

PHP provides a commonly used function to determine empty, that isempty().

empty()This function has a special property, that is, it can simultaneously determine whether a "variable" exists and whether it is "empty".

When the parameter of empty() is a It is best not to use it when it is an array or object, because empty() cannot detect the fact that the attribute actually exists but the value is empty, but only detects whether the array or object itself exists.

Let’s take a look Here is a code example of using the empty() function to determine whether a PHP array is empty:

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

Method 2: Use the count function

count can be used in PHP () function to count the number of array elements. We can determine whether a PHP array is empty based on the number of array elements. When the number of array elements is 0, the array is empty.

Next let’s look at the usage of function count():

Now that we understand the usage of function count(), let’s look at the judgment Implementation code for whether the PHP array is empty:

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

Method 3: Use the isset() function

In PHP, the isset() function detects whether the variable has been set and is not empty , that is, the isset() function can be used to determine whether a variable is set and not null. We can use the isset() function to determine whether the array is empty as follows:

$arr = array();
if(isset($arr) == false) {
   echo "数组为空";
}
else {
   echo "数组不为空";
}

Method 4: Use the array key name traversal method

In PHP, the array does not Empty if any key is set or if the key is not 0. So we can first use the array_keys() function to get all the keys in the array, and then use the foreach statement to traverse the array to determine whether it is empty.

The specific implementation method is as follows:

$arr = array('a'=>1,'b'=>2,'c'=>3);
$keys = array_keys($arr);
if(count($keys) == 0) {
    echo "数组为空";
}
else {
    echo "数组不为空";
}

Method 5: Use array_values ​​function method

In addition to judging whether the number of keys is 0, We can also use the value of the array to determine whether the array is empty. For an empty array, the total number of values ​​traversed is 0. So we can use the array_values() function to get all the values ​​in the array, and then use the count() function to determine whether the array is empty.

Code implementation:

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

The above are the five ways to determine whether a PHP array is empty. Each method has its own characteristics and different application scenarios. In the actual development process, we can choose the most appropriate method to make judgments based on our own needs.

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