<?php
//printf
$str1 = "中国";
$str2 = "中华人民共和国";
$n = 12;
printf("%14s \r\n", $str1);
printf($str2);
echo "\r\n";
printf("%'*14s \r\n", $str1);
printf("%12.3f \r\n", $n);

//sprintf
$a = sprintf("%'*14s \r\n", $str1);
echo $a;

//vsprintf
$str1 = ["中国", "中华人民共和国"];
$a = vsprintf("%'*14s \r\n  %s", $str1);
echo $a;
?>

<?php
    $num = 12;
    printf("小数格式%1\$.2f<br>整数格式 %1\$u", $num);

    $A = 92;
    $B = 23.2;
    printf("变量A小数格式：%1\$.2f<br>变量B整数格式：%2\$u<br> 变量A整数格式：%1\$u", $A, $B);
?>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<?php
    $A = "hello";
    $B = "我是中国人";
    echo "变量A的长度：".strlen($A)."<br>";
    echo "变量B的长度：".strlen($B)."<br>";
    echo "变量B的长度：".mb_strlen($B)."<br>";
?>

<?php
$str = "We want To FLY";             //定义字符串类型的变量
echo strtolower ($str) . "<br>";     //输出转换为小写的字符串
echo strtoupper($str) . "<br>";      //输出转换为大写的字符串
echo ucfirst($str) . "<br>";         //输出转换为首字母大写的字符串
echo lcfirst($str) . "<br>";         //输出转换为首字母小写的字符串
echo ucwords($str) . "<br>";         //输出转换为单词首字母大写的字符串
echo $str;                           //输出原字符串
?>

<?php
    $str = "123PHP 教程456";
    var_dump(trim($str,'1..6'));
    var_dump(ltrim($str,'1..6'));
    var_dump(rtrim($str,'1..6'));
?>

<?php
//strstr
$s = "先天下之忧而忧，后天下之乐而乐";
$pos1 = strstr($s, "后");
var_dump($pos1);
$pos1 = strstr($s, "，", true);
var_dump($pos1);

//strpos
$pos1 = strpos("ABCabc", "C");
var_dump($pos1);
$pos1 = strpos("ABCabc", "1");
var_dump($pos1);
$pos1 = strpos("ABCabc", "A");
var_dump($pos1);
?>

<?php
echo ord("a");     //输出97,如果包含多个字符，只返回第一个字符的ASCII码
echo chr(98);     //输出"b"
?>

<?php
echo strcmp("我们", "你们"); // =1 "我们" > "你们" "women" > "nimen"

$A = "hello,My name is Tom";
$B = "hello,my name is Tom";
echo strncmp($A, $B, 6);
echo strncmp($A, $B, 8);
?>

<?php 
    // str_replace
    $arr = array("blue","red","green","yellow");
    print_r(str_replace("red","pink",$arr,$i));
    echo "Replacements: $i";

    $find = array("Hello","world");
    // $replace = array("B");
    $replace = array("B", "c");
    $arr = array("Hello","world","!");
    print_r(str_replace($find,$replace,$arr, $b));
    echo $b;

    //substr_replace
    //从字符串的第 6 个位置开始替换（把 "world" 替换成 "earth"）：
    echo substr_replace("Hello world","earth",6);

    //从字符串结尾的第 5 个位置开始替换（把 "world" 替换成 "earth"）：
    echo substr_replace("Hello world","earth",-5);

    //在 "world" 开头插入 "Hello"：
    echo substr_replace("world","Hello ",0,0);
?>

<?php
$str = "This is some <b>bold</b> text.";
echo htmlspecialchars($str);
?>

<?php
$str = "This is some <b>bold</b> text.";
echo htmlspecialchars_decode($str);
?>

<?php
echo nl2br("foo isn't\n bar");
?>

<?php
$str = "Hello world. I love Shanghai!";
print_r (explode(" ", $str));
print_r (explode(" ", $str, 2));
print_r (explode(" ", $str, -2));
?>

<?php
$arr = array('Hello','World!','I','love','Shanghai!');
echo implode(" ", $arr);
?>

<?php
//php8 第二参数必填
//注册时 通过crypt生产加密密码 保存到数据库
//每次的值不同，密码mypassword生成 11s6ek9C15TTI
$hashed_password = crypt('mypassword', mt_rand().'-'.time());
//登陆时，取得已加密的字符串，与登陆密码比对
$user_input = "mypassword";
$get_hashed_password = "11s6ek9C15TTI";
if (hash_equals($get_hashed_password, crypt($user_input, $get_hashed_password))) {
   echo "Password verified!";
}

//官方推荐使用password_hash()
$hashed_password = password_hash("mypassword", PASSWORD_DEFAULT); //$2y$10$IPPyAtARiLU0j/jn9cqwiewi9LYYpLioY35h4gWNurHBZX1y2F5jW
$user_input = "mypassword";
$get_hashed_password = '$2y$10$IPPyAtARiLU0j/jn9cqwiewi9LYYpLioY35h4gWNurHBZX1y2F5jW';
if (password_verify($user_input, $get_hashed_password)) {
   echo "Password verifie!";
}
?>

<?php
//substr
echo substr("Hello world",10)."<br>";
echo substr("Hello world",1)."<br>";
echo substr("Hello world",3)."<br>";
echo substr("Hello world",7)."<br>";
 
echo substr("Hello world",-1)."<br>";
echo substr("Hello world",-10)."<br>";
echo substr("Hello world",-8)."<br>";
echo substr("Hello world",-4)."<br>";

//mb_substr
echo mb_substr("PHP基础教程", 3, 2);
?>

<?php
// 生成验证码
$a = "ABCDE12345";
echo substr(str_shuffle($a), 0, 4);
?>

<?php
//贪婪匹配
preg_match('/p.*h/', 'phphphph', $matches);
print_r($matches);  // 输出结果:Array([0] => phphphph)

//惰性匹配
preg_match('/p.*?h/', 'phphphph', $matches);
print_r($matches);  // 输出结果:Array([0] => ph)
?>

<?php
preg_match_all('/con/i', "ConABBcconlkbcOn", $matches);
print_r($matches);

preg_match_all('/^P.*/m', "PHP\nPc", $matches);
print_r($matches);

preg_match_all('/Hi.*my/s', "Hi\nmy", $matches);
print_r($matches);

preg_match_all('/n e e d/x', "need", $matches);
print_r($matches);
?>

<?php
$subjects = array("Mechanical Engineering", "Medicine", "Social Science","Agriculture", "Commercial Science", "Politics");
//匹配所有仅由一个单词组成的科目名，"i"表示不区分大小写
$alonewords = preg_grep("/^[a-z]*$/i", $subjects);
var_dump($alonewords);
?>

<?php
$str = "php功能强大，学习php是一件快乐的事。";
$preg = "/[php]+/";
$a = preg_match($preg, $str, $match1);
echo $a."<br>";
var_dump($match1);

$b = preg_match_all($preg, $str, $match2);
echo "<p>".$b."<br>";
var_dump($match2);
?>

<?php
$k1 = "$40 for a g3/400";
$k2 = preg_quote ($k1, "/");
echo "原字符串：".$k1. "<br>";
echo "转义字符串:".$k2;
?>

<?php
$k1 = "The quick brown fox jumped over the lazy dog.";    //定义变量
$k2 = preg_replace('/\s/','-',$k1);
//定义变量，并将替换后的字符串赋给它
echo "原字符串：".$k1. "<br>";                    //输出字符串变量$k1
echo "替换空格后的字符串:".$k2;                  //输出字符串变量$k2
?>

<?php
$str = "php mysql,apache ajax";           //定义字符串变量
$keywords = preg_split("/[\s,]+/", $str);
//定义变量，并将分割后的字符串赋给它
print_r($keywords);                      //输出分割后的字符串组成的数组
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>留言簿</title>
</head>
<body>
    <form action="" method="POST">
        <p>您的Email地址：</p>
        <input type="text" name="Email" size="31"><br>
        <p>您的留言：</p>
        <textarea name="note" cols="30" rows="10"></textarea><br>
        <input type="submit" name="bt1" value="提交">
        <input type="reset" name="bt2" value="清空">
    </form>
</body>
</html>
<?php
    if(isset($_POST['bt1'])){
        $email = $_POST['Email'];
        $note = $_POST['note'];
        if(!$email || !$note){
            echo "<script>alert('Email地址和留言内容必须填写')</script>";
            return;
        }
        if(!preg_match('/^[_a-zA-Z0-9-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-]+$/', $email)){
            echo "<script>alert('Email地址格式错误')</script>";
            return;
        }
        //分割邮箱 转数组
        $emails = explode("@", $email);

        //将留言中的“我”替换为“本人”
        $newNote = str_replace("我", "本人", $note);
        echo <<<ABC
        <font face="黑体" size=4>
            用户{$emails[0]}您好！&nbsp;
            您是{$emails[1]}的网友！<br>
            您的留言是：<br>
            &nbsp;&nbsp;{$newNote}
        </font>
ABC;
    }
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>新用户注册</title>
</head>
<body>
<form action="" method="post">
    <fieldset>
        <legend>新用户注册</legend>
        <p>用户名：<input type="text" name="username"/><span>* 不超过10个字符（数字，字母和下划线）</span></p>
        <p>密码：<input type="password" name="password"/><span>* 4-14个数字</span></p>
        <p>手机号码：<input type="text" name="phone"/><span>* 11位数字，第一位为1</span></p>
        <p>邮箱：<input type="text" name="email"/><span>* 有效的邮箱地址</span></p>
        <input type="submit" name="submit" value="注册">
        <input type="reset" name="submit2" value="取消">
    </fieldset>
</form>
</body>
</html>
<?php
    if(isset($_POST['submit'])){
        $username = $_POST['username'];
        $password = $_POST['password'];
        $phone = $_POST['phone'];
        $email = $_POST['email'];
        
        $checkName = preg_match('/^\w{1,10}$/', $username);
        $checPassword = preg_match('/^\d{4,14}$/', $password);
        $checkPhone = preg_match('/^1\d{10}$/', $phone);
        $checkEmail = preg_match('/^[_a-zA-Z0-9-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-]+$/', $email);
        
        if($checkName && $checPassword && $checkPhone && $checkEmail){
            echo "<script>alert('注册成功！')</script>";
        } else {
            echo "<script>alert('注册失败！')</script>";
        }
    }
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>欢迎访问小说网</title>
</head>
<body>
    <table width = 400 align="center" border = 1>
        <tr><td align="center">PHP读取小说</td></tr>
        <tr>
            <td>
    <?php
        $page = isset($_GET['page']) ? $_GET['page']: 1;
        $charSize = 400;
        $counter = file_get_contents("1.txt");
        $length = mb_strlen($counter);
        $pageCount = ceil( $length / $charSize);
        echo mb_substr($counter, ($page-1)*$charSize, $charSize);
    ?>                    
            </td>
        </tr>
    </table>
    <table align="center" width = 400>
        <tr>
            <td>页次：<?php echo $page.'/'.$pageCount.'页'; ?></td>
            <td>分页：
                <?php
                    if($page != 1){
                        echo "<a href='demo.php?page=1'>首页</a>";
                        echo "<a href='demo.php?page=".($page-1)."'>上一页</a>";
                    }
                    if($page < $pageCount){
                        echo "<a href='demo.php?page=".($page+1)."'>下一页</a>";
                        echo "<a href='demo.php?page={$pageCount}'>尾页</a>";
                    }
                ?>
            </td>
        </tr>
    </table>
</body>
</html>