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In PHP, assert() and array_diff_key() are two very useful functions. The former is usually used to make assertions, checking whether a certain condition holds, while the latter is used to compare the keys of two arrays and return keys that are not in the second array. We can use these two functions in combination to implement a simple and effective assertion logic that helps us perform fast conditional checks in our code. This article will explain in detail how to use these two functions to implement simple assertion logic.
The assert() function is mainly used in PHP to check whether a certain condition is true. If the condition is false, an error is triggered. This function is often used to debug and test code, ensuring that critical conditions are always true during development.
assert(expression);
Expression is a conditional expression that needs to be validated. If the result of the expression is false, an error will be triggered.
$age = 20;
assert($age > 18); // if $age Less than or equal to 18，A warning will be triggered
In the above code, assert() is used to check whether $age is greater than 18. If the condition is false, PHP will trigger a warning.
The array_diff_key() function is used to compare the keys of two arrays and returns a new array containing the key-value pairs in the first array but not in the second array.
array_diff_key(array $array1, array $array2): array
array1 and array2 are two arrays to be compared.
This function returns an array containing all keys in array1 but not in array2 .
$array1 = ['a' => 1, 'b' => 2, 'c' => 3];
$array2 = ['a' => 4, 'c' => 5];
$result = array_diff_key($array1, $array2);
print_r($result);
Output:
Array
(
[b] => 2
)
In the above code, array_diff_key() compares the keys of $array1 and $array2 and returns a new array that contains only keys that are in $array1 but not in $array2 .
Combining assert() and array_diff_key() , we can implement simple assertion logic by checking whether an array contains the necessary keys.
Suppose we have an associative array that stores the basic information of the user, including keys such as name , email , and age . We want to verify that the array contains at least these three keys. If any one is missing, we can trigger an assertion error.
<?php
// Assume this is the incoming user data
$userData = [
'name' => 'John Doe',
'email' => 'john.doe@m66.net',
// 'age' Key missing
];
// Need keys
$requiredKeys = ['name', 'email', 'age'];
// Comparison key
$missingKeys = array_diff_key(array_flip($requiredKeys), $userData);
// if有缺失的键，Triggers assertion
assert(empty($missingKeys), 'Missing the necessary keys：' . implode(', ', array_keys($missingKeys)));
// if断言通过，Continue to execute
echo 'Complete user data，Continue to process...';
?>
User data: We define a $userData array that contains the basic information of the user. Here we deliberately missed the age key.
Required Keys: The $requiredKeys array contains all the keys we expect to appear in the user data.
Compare keys: Use array_diff_key() to compare the keys in $userData with the keys in $requiredKeys . If there are missing keys, the $missingKeys array will contain these missing keys.
Assertion: If the $missingKeys array is not empty, it means there is a missing key. We trigger an assertion error through the assert() function and output the missing key name.
By combining assert() and array_diff_key() , we can perform assertion checks on array data very conveniently. Especially when processing user input or data verification, this method can ensure data integrity and avoid errors caused by the lack of necessary data in subsequent code. As a lightweight debugging tool, assert() can help us capture potential problems in a timely manner during the development stage, while array_diff_key() provides us with a concise and efficient way to compare key-value pairs.
In this way, you can be more confident when writing code and ensure the stability and reliability of your program.
