PHP Warning: array_merge(): Argument solution

PHP Warning: array_merge(): Argument solution

In PHP development, we often encounter the PHP Warning: array_merge(): Argument error message. What does this mean?

PHP Warning: array_merge(): Argument error is caused because one or more parameters are not of array type. The array_merge() function merges one or more arrays, and if any parameter is not of array type, an Argument error will occur.

So how to solve this problem? Here are several methods for you.

Method 1: Check whether the parameter is an array type

Before using the array_merge() function, you need to ensure that the parameter is an array type. You can use the is_array() function to determine.

For example, in the following code, $arr1 and $arr2 are both array types, but $arr3 is a string type, so it will cause an Argument error:

$arr1 = array('a', 'b', 'c');
$arr2 = array('d', 'e', 'f');
$arr3 = 'g, h, i';

$merged_arr = array_merge($arr1, $arr2, $arr3); // Argument错误

Therefore, we need to use is_array () function to check whether the parameter is an array type. If not, it can be converted to an array type:

$arr1 = array('a', 'b', 'c');
$arr2 = array('d', 'e', 'f');
$arr3 = 'g, h, i';

if (is_array($arr3)) {
    $merged_arr = array_merge($arr1, $arr2, $arr3);
} else {
    $arr3 = explode(',', $arr3);
    $merged_arr = array_merge($arr1, $arr2, $arr3);
}

Judged by the is_array() function. If $arr3 is not an array type, use the explode() function to Convert strings to array types and then merge them.

Method 2: Use the array_values() function

If an Argument error occurs, you can also try to use the array_values() function to convert the parameter to a numeric array type.

For example, in the following example, $arr1 and $arr2 are associative array types, and $arr3 is a numeric array type:

$arr1 = array('a' => 1, 'b' => 2, 'c' => 3);
$arr2 = array('d' => 4, 'e' => 5, 'f' => 6);
$arr3 = array(7, 8, 9);

$merged_arr = array_merge($arr1, $arr2, $arr3); // Argument错误

Since $arr1 and $arr2 are associative array types, $ arr3 is a numeric array type, causing an Argument error. Therefore, you can use the array_values() function to convert $arr1 and $arr2 to numeric array types, and then merge them:

$arr1 = array('a' => 1, 'b' => 2, 'c' => 3);
$arr2 = array('d' => 4, 'e' => 5, 'f' => 6);
$arr3 = array(7, 8, 9);

$arr1_values = array_values($arr1); // 数值数组类型
$arr2_values = array_values($arr2); // 数值数组类型

$merged_arr = array_merge($arr1_values, $arr2_values, $arr3);

Use the array_values() function to convert $arr1 and $arr2 to numeric array types, and then merge merge.

Method 3: Use the sign operator

Using the sign operator to merge arrays can avoid Argument errors, because the sign operator will only merge the values ​​in the array, not Add new keys or change existing keys.

For example, in the following code, $arr1 and $arr2 are both associative array types, and $arr3 is a numeric array type:

$arr1 = array('a' => 1, 'b' => 2, 'c' => 3);
$arr2 = array('d' => 4, 'e' => 5, 'f' => 6);
$arr3 = array(7, 8, 9);

$merged_arr = $arr1 + $arr2 + $arr3; 

Use the sign operator to merge to avoid Argument errors. Appear.

To sum up, the PHP Warning: array_merge(): Argument error is caused by one or more parameters not being of array type. Argument errors can be avoided by checking whether the argument is of array type, using the array_values() function, and using the sign operator. When writing PHP code, you need to pay attention to the correctness of parameter types to avoid Argument errors.

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