Complete PHP function library

The PHP function library provides a wide range of tools for completing a variety of programming tasks, including string manipulation, array manipulation, and interaction with databases. These functions help write PHP applications efficiently. In addition, this article also shows a practical case of using the PHP function library to dynamically generate HTML tables, which can obtain data from the database and display it in the table.

PHP Function Library: A Comprehensive Guide

PHP provides an extensive library of functions to solve a wide range of programming problems Tasks, from string manipulation to database interaction. Understanding the purpose and usage of these functions is crucial to writing PHP applications efficiently.

String function

• strlen(): Returns the length of the string.
• strtoupper(): Convert the string to uppercase.
• strtolower(): Convert the string to lowercase.
• substr(): Extract a substring from a string.
• str_replace(): Replace another string in a string with a new string.

Array function

• sort(): Sort the array.
• count(): Returns the number of elements in the array.
• array_merge(): Merge two or more arrays.
• array_keys(): Returns an array of all keys of the array.
• in_array(): Check whether a value exists in the array.

Date and time functions

• date(): Format the given date and time.
• time(): Returns the current timestamp.
• mktime(): Creates a timestamp from the specified date and time.
• strtotime(): Convert the date and time represented by a string into a timestamp.
• gmdate(): Date-time formatted as Greenwich Mean Time (GMT).

Database functions

• mysqli_connect(): Establish a connection to the MySQL database.
• mysqli_query(): Execute a SQL query.
• mysqli_fetch_assoc(): Get an associative array from the result set.
• mysqli_num_rows(): Returns the number of rows in the result set.
• mysqli_close(): Close the connection to the MySQL database.

Practical case: Dynamically generate HTML table

<?php

// 连接到数据库
$mysqli = mysqli_connect("hostname", "username", "password", "database");

// 执行 SQL 查询
$result = mysqli_query($mysqli, "SELECT * FROM users");

// 创建 HTML 表格
echo "<table>";
echo "<tr><th>ID</th><th>姓名</th><th>电子邮件</th></tr>";

// 遍历结果集并生成表行
while ($row = mysqli_fetch_assoc($result)) {
    echo "<tr><td>" . $row['id'] . "</td><td>" . $row['name'] . "</td><td>" . $row['email'] . "</td></tr>";
}

// 关闭数据库连接
mysqli_close($mysqli);

echo "</table>";

?>

The above script connects to the database, executes a query, and then dynamically generates an HTML table containing the query results.

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