这是一份全面的 php 备忘单,涵盖基本语法和函数:
基本
<?php // single-line comment
/*
multi-line comment
*/
// variables
$variable_name = "value"; // string
$number = 123; // integer
$float = 12.34; // float
$boolean = true; // boolean
$array = [1, 2, 3]; // array
// constants
define("constant_name", "value");
const another_constant = "value";
?>
数据类型
- 字符串:“你好,世界!”
- 整数:123
- 浮动:12.34
- 布尔值:真或假
- 数组:[“苹果”,“香蕉”,“樱桃”]
- 对象
- null
弦乐
<?php $str = "hello";
$str2 = 'world';
$combined = $str . " " . $str2; // concatenation
// string functions
strlen($str); // length of a string
strpos($str, "e"); // position of first occurrence
str_replace("e", "a", $str); // replace all occurrences
?>
数组
<?php $array = [1, 2, 3];
$assoc_array = ["key1" => "value1", "key2" => "value2"];
// array functions
count($array); // count elements
array_push($array, 4); // add an element
array_merge($array, [4, 5]); // merge arrays
in_array(2, $array); // check if element exists
?>
控制结构
如果别的
<?php if ($condition) {
// code to execute if true
} elseif ($another_condition) {
// code to execute if another condition is true
} else {
// code to execute if all conditions are false
}
?>
转变
<?php switch ($variable) {
case "value1":
// code to execute if variable equals value1
break;
case "value2":
// code to execute if variable equals value2
break;
default:
// code to execute if no case matches
}
?>
循环
<?php // for loop
for ($i = 0; $i < 10; $i++) {
// code to execute
}
// while loop
while ($condition) {
// code to execute
}
// do-while loop
do {
// code to execute
} while ($condition);
// foreach loop
foreach ($array as $value) {
// code to execute
}
?>
功能
<?php function functionname($param1, $param2) {
// code to execute
return $result;
}
$result = functionname($arg1, $arg2);
?>
超全局变量
- $_get – 通过 url 参数发送的变量
- $_post – 通过 http post 发送的变量
- $_request – 通过 get 和 post 发送的变量
- $_server – 服务器和执行环境信息
- $_session – 会话变量
- $_cookie – http cookie
文件处理
<?php // reading a file
$file = fopen("filename.txt", "r");
$content = fread($file, filesize("filename.txt"));
fclose($file);
// writing to a file
$file = fopen("filename.txt", "w");
fwrite($file, "hello, world!");
fclose($file);
?>
错误处理
<?php try {
// code that may throw an exception
if ($condition) {
throw new exception("error message");
}
} catch (exception $e) {
// code to handle the exception
echo "caught exception: " . $e->getmessage();
} finally {
// code to always execute
}
?>
数据库(mysqli)
<?php // create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// check connection
if ($conn->connect_error) {
die("connection failed: " . $conn->connect_error);
}
// select data
$sql = "select id, firstname, lastname from myguests";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
echo "id: " . $row["id"]. " - name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
}
} else {
echo "0 results";
}
$conn->close();
?>
会话管理
<?php // start session
session_start();
// set session variables
$_session["username"] = "johndoe";
$_session["email"] = "john@example.com";
// get session variables
echo $_session["username"];
// destroy session
session_destroy();
?>
包含和要求
<?php include 'filename.php'; // Includes file, gives a warning if not found
require 'filename.php'; // Includes file, gives a fatal error if not found
include_once 'filename.php'; // Includes file once, checks if already included
require_once 'filename.php'; // Requires file once, checks if already included
?>
本备忘单涵盖了 php 中的基本概念和常用功能。如果您需要有关任何特定主题的更多详细信息,请告诉我!