Detailed explanation of PHP special functions

This article introduces the special functions provided by PHP to simplify common programming tasks, including: Type conversion functions: Determine, obtain and cast variable types. String manipulation functions: Get length, convert case, and remove whitespace characters. Array manipulation functions: append, remove, and add elements to the beginning or end of an array. Number manipulation functions: Returns absolute value, maximum value, minimum value, and rounding. Date and time functions: Get and format dates and times, and parse dates and times into timestamps. Mastering these special functions is crucial to efficient PHP development, and using them appropriately can simplify your code and improve application performance.

Detailed explanation of PHP special functions

PHP provides many special functions to simplify common programming tasks. This article will introduce these functions in detail and provide practical examples to illustrate.

1. Type conversion function

• type:Determine the type of the variable
• gettype:Return the name of the variable type
• settype:Force the variable to the specified type

Actual case:Confirm the input value Type

if (type($input) == "string") {
  // ... 处理字符串
} elseif (type($input) == "boolean") {
  // ... 处理布尔值
} else {
  // ... 处理其他类型
}

2. String operation function

• strlen：Get the string length
• strtoupper: Convert the string to uppercase
• strtolower: Convert the string to lowercase
• trim: Remove string two White space characters at the end

Practical case:Verify the validity of the user name

$username = trim($_POST['username']);
if (strlen($username) < 6 || strlen($username) > 20) {
  // ... 处理无效用户名
}

3. Array operation function

• array_push: Append elements to the end of the array
• array_pop: Remove and return the last element of the array
• array_unshift: Add elements at the beginning of the array
• array_shift: Remove and return the first element of the array

Practical case:From Delete an item from the shopping cart

$cart = [
  'item1', 'item2', 'item3'
];

$item = $_GET['item'];
$key = array_search($item, $cart);

if ($key !== false) {
  array_splice($cart, $key, 1);
}

4. Numeric operation function

• abs: Return absolute value
• max: Returns the maximum value
• min: Returns the minimum value
• round: Rounds the number

Practical case: Calculate the total price of the shopping cart

$prices = [10.50, 12.25, 8.75];
$total = round(array_sum($prices), 2);

5. Date and time functions

• date: Return the current date and time
• strftime: Format date and time
• mktime: Parse the date and time For timestamp
• time:Return the current timestamp

Practical case:Create order date stamp

$order_date = time();
strftime('%Y-%m-%d %H:%M:%S', $order_date);

Mastering these special functions is essential for efficient PHP development. Used wisely, they can simplify code, reduce duplication, and improve application performance.

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