Input and output operations in PHP

With the rapid development of network technology, PHP has become one of the most popular and widely used scripting languages ​​in developing dynamic web pages, Web applications, content management systems and e-commerce platforms. In these development processes, input and output operations are one of the natural operations. This article will discuss the input and output operations in PHP to help readers better master the application of PHP.

1. Output operation

There are mainly four types of output statements in PHP:

(1)echo

echo is PHP The simplest output statement, it can output one or more strings. The echo statement does not require parentheses, and the syntax format is as follows:

echo 输出字符串

The sample code is as follows:

<?php
echo "hello,world!";
?>

Output result:

hello,world!

(2) print

print You can also output one or more strings, similar to echo. The difference is that the print statement must take one parameter and the return value is always 1. The syntax format of the print statement is as follows:

print 输出字符串

The sample code is as follows:

<?php
print "hello,world!";
?>

Output result:

hello,world!

(3) print_r

print_r is mainly used for output Variables of composite types such as arrays and objects. It can print the contents of an entire array or object. The syntax format of the print_r statement is as follows:

print_r 输出复合变量

The sample code is as follows:

<?php
$arr = array("apple", "banana", "orange");
print_r($arr);
?>

Output result:

Array
(
    [0] => apple
    [1] => banana
    [2] => orange
)

(4) var_dump

Similar to print_r, var_dump Used to print detailed information about variables, including variable type, length, value, etc. The syntax format of var_dump is as follows:

var_dump 输出变量

The sample code is as follows:

<?php
$arr = array("apple", "banana", "orange");
var_dump($arr);
?>

Output result:

array(3) {
  [0]=>
  string(5) "apple"
  [1]=>
  string(6) "banana"
  [2]=>
  string(6) "orange"
}

2. Input operation

provided by PHP There are several ways to receive data submitted by the client or user, including the following:

(1) GET

passes parameters in the form of key-value pairs in the URL, which can be passed $_GET array reads data. The GET method is a simple HTTP request method, which is unsafe but fast. GET requests are generally used to obtain information, not to modify it. The syntax format of GET is as follows:

http://example.com/test.php?key1=value1&key2=value2

The sample code is as follows:

<?php
$name = $_GET['name'];
echo "Hello, $name!";
?>

(2) POST

Put the data in the body part of the request, which can be read through the $_POST array data. The POST method is safe but slow. POST requests are usually used for operations such as modifying information and logging in. The syntax format of POST is as follows:

<form method="post" action="test.php">
    <input type="text" name="name">
    <input type="submit" value="Submit">
</form>

The sample code is as follows:

<?php
$name = $_POST['name'];
echo "Hello, $name!";
?>

(3) REQUEST

supports obtaining both GET and POST data at the same time, which can be read through the $_REQUEST array Get data. Compared with the $_GET and $_POST arrays, the $_REQUEST array is less efficient and more dangerous, and is not recommended for frequent use. The syntax format of REQUEST is as follows:

$value = $_REQUEST['key'];

(4) COOKIE

Store the data in the cookie in the client browser, and the data can be read through the $_COOKIE array. Since cookies are stored on the client side, cookies have a small capacity limit (generally 4KB) and are not suitable for storing excessively large data or sensitive data. The syntax format of COOKIE is as follows:

$value = $_COOKIE['key'];

The sample code is as follows:

<?php
$name = $_COOKIE['name'];
echo "Hello, $name!";
?>

(5) SESSION

Store the data in the Session on the server side and can read it through the $_SESSION array data. Compared with Cookie, Session is more secure and has a larger storage capacity (generally 8KB). The syntax format of SESSION is as follows:

$value = $_SESSION['key'];

The sample code is as follows:

<?php
session_start();
$_SESSION['name'] = "PHP";
$name = $_SESSION['name'];
echo "Hello, $name!";
?>

To sum up, the input and output operations in PHP are an indispensable part of the development process, and developers should understand and be proficient in it. master. When performing input and output operations, pay attention to safety and efficiency, and choose the appropriate method according to the actual situation.

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