php所有函数中能用的变量，php数组函数，6个

PHP is a server-side scripting language used for web development. It is an open-source scripting language that is used for creating dynamic web pages. PHP stands for Hypertext Preprocessor, which means that it processes the code before it is displayed in the browser. In this article, we will take a closer look at PHP variables and array functions.

PHP variables

A variable is a name that represents a storage location in memory that contains a value. PHP variables start with a dollar sign ($) followed by a name. They can hold many types of data such as strings, integers, floats, booleans, and arrays. The scope of a PHP variable is determined by where it is declared.

PHP has a variety of built-in variables that are automatically available in every script. Some of these variables are:

- $_SERVER: Contains information about the server and the execution environment.

- $_GET: Contains information passed via GET method.

- $_POST: Contains information passed via POST method.

- $_COOKIE: Contains information stored on the client's computer.

- $_SESSION: Contains information stored on the server-side.

- $GLOBALS: Allows access to all global variables from anywhere in the script.

PHP Arrays

An array is a data structure that stores a collection of data values, each identified by an index or a key. PHP arrays can hold a variety of data types such as strings, integers, floats, and even other arrays. PHP arrays can be created as either indexed arrays or associative arrays.

Indexed Arrays

An indexed array is an array where each element is assigned a numerical index starting with zero. The basic syntax for creating an indexed array is:

```

$array = array(value1, value2, ...);

```

For example:

```

$fruits = array("apple", "banana", "orange");

```

In the above example, $fruits is an array of strings.

Associative Arrays

An associative array is an array where each element can be assigned a name, or a key, that refers to the element's value. The basic syntax for creating an associative array is:

```

$array = array(key1 => value1, key2 => value2, ...);

```

For example:

```

$age = array("John" => 25, "Mary" => 33, "Tony" => 47);

```

In the above example, $age is an array of integers, with each element assigned a name.

PHP Array Functions

PHP has a wide range of built-in array functions that can be used to manipulate arrays. Some of the most commonly used array functions are:

1. count():

The count() function is used to count the number of elements in an array.

```

$fruits = array("apple", "banana", "orange");

$count = count($fruits);

echo $count; //Output: 3

```

2. array_push():

The array_push() function is used to add one or more elements to the end of an array.

```

$fruits = array("apple", "banana");

array_push($fruits, "orange");

print_r($fruits); //Output: Array ( [0] => apple [1] => banana [2] => orange )

```

3. array_pop():

The array_pop() function is used to remove the last element from an array.

```

$fruits = array("apple", "banana", "orange");

array_pop($fruits);

print_r($fruits); //Output: Array ( [0] => apple [1] => banana )

```

4. array_shift():

The array_shift() function is used to remove the first element from an array.

```

$fruits = array("apple", "banana", "orange");

array_shift($fruits);

print_r($fruits); //Output: Array ( [0] => banana [1] => orange )

```

5. array_unshift():

The array_unshift() function is used to add one or more elements to the beginning of an array.

```

$fruits = array("apple", "banana");

array_unshift($fruits, "orange");

print_r($fruits); //Output: Array ( [0] => orange [1] => apple [2] => banana )

```

6. array_reverse():

The array_reverse() function is used to reverse the order of elements in an array.

```

$fruits = array("apple", "banana", "orange");

$reverse = array_reverse($fruits);

print_r($reverse); //Output: Array ( [0] => orange [1] => banana [2] => apple )

```

In conclusion, PHP is a powerful server-side scripting language that is used for web development. Variables and arrays are an essential part of PHP, and there are many functions available to manipulate them. The above-mentioned array functions are just a few examples of the many built-in functions available in PHP. Understanding how to use these functions will help in creating robust and dynamic web applications. 如果你喜欢我们三七知识分享网站的文章， 欢迎您分享或收藏知识分享网站文章 欢迎您到我们的网站逛逛喔！https://www.ynyuzhu.com/