How to determine whether an array has a value in php

3 ways to determine: 1. Use the empty() function to determine whether the array is empty. The syntax is "empty($array)". If it is not empty, it means there is a value in the array, otherwise there is no value. 2. Use the count() function to determine whether the array length is 0. The syntax is "count($array) == 0". If it is 0, it means there is no value in the array, otherwise it means there is a value. 3. Use the "===" operator to determine whether the array is "[]" (empty array). The syntax is "array ===[]". If TRUE is returned, there is no value in the array.

The operating environment of this tutorial: windows7 system, PHP8.1 version, DELL G3 computer

Method 1: Use empty() function

#empty() function is used to check whether a variable is empty.

If an array has no value, the array is an empty array.

Therefore, you only need to use the empty() function to determine whether the array is empty, and then you can determine whether there is a value in the array.

<?php
header("content-type:text/html;charset=utf-8");
// 声明一个数组
$array = array(null);
var_dump($array);
// 检查数组是否为空
if(empty($array))
    echo "数组为空，里面没有值";
else
    echo "数组不为空，里面有值";
?>

Description:

empty() determines whether a variable is considered empty. When a variable does not exist, or its value is equal to FALSE, then it is considered not to exist. empty() does not generate a warning if the variable does not exist.

Note: Any uninitialized variable, a variable with a value of 0 or false or an empty string "" or null, an empty array, or an object without any attributes will be judged as empty==true

Returns FALSE when the variable exists and is a non-empty and non-zero value, otherwise returns TRUE.

Method 2: Use the count() function

The count() function can calculate the length of the array.

If an array has a value, the array length must be greater than 0; if there is no value, the array length is 0.

Therefore, we canuse the count() function to calculate the length of the array, and then determine whether the length is 0; if it is 0, there is no value, otherwise there is a value.

<?php
header("content-type:text/html;charset=utf-8");
// 声明一个空数组
$array = array();
var_dump($array);
// 检查数组是否为空
if(count($array) == 0)
    echo "数组为空，里面没有值";
else
    echo "数组不为空，里面有值";
?>

Description:

count() function returns the number of elements in the array, which is the length of the array.

count($arr,$m)

$m: is an optional parameter and can be omitted.

• If the $m parameter is omitted, or set to COUNT_NORMAL or 0, the count() function will not detect multidimensional arrays;

• If If $m is set to COUNT_RECURSIVE or 1, the count() function will recursively calculate the number of elements in the array, which is especially useful for calculating the number of elements in multi-dimensional arrays.

Method 3: Use the "===" operator to determine whether the array is "[]"

" ===" is a comparative equality operator

• If TRUE is returned, there is no value in it
  

• If FALSE is returned, Then there is a value
  

<?php
header("content-type:text/html;charset=utf-8");
// 声明一个数组
$array = array(1);
var_dump($array);
// 检查数组是否为空
if($array===[])
    echo "数组为空，里面没有值";
else
    echo "数组不为空，里面有值";
?>

Recommended learning: "PHP Video Tutorial", "PHP ARRAY 》

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