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PHP-day01

2024-09-08 16:17:09   215人阅读

<!--php嵌入HTML-->
<html>
<head>
    <title>day01</title>
</head>
<body>
<h2>
    <?php echo "Hello Php" ?>
</h2>
</body>
</html>
<?php
/*$声明变量并赋值*/
    $a = 10;
    $b = ‘Lemon‘;
    $c = ‘柠檬‘;
    $d = true;
    $f = 55.55;
    $key = $a;
    $a=$b=$c=$d="value";
/*  显示数据类型
    int:整型
    sting：字符串
    float :浮点型
    一个汉字占3个字符长度*/
    var_dump($a);
    var_dump($b);
    var_dump($c);
    var_dump($d);
    var_dump($f);
    var_dump($key);
    /*isset
     * 检测当前数据是否被初始化
     * 数据不定义不会分配内存空间*/
    $num;
    if(isset($num)){
        echo"num被定义了";
    }else{
        echo"num没有被定义";
    }
echo"<br>";
    /*unset：释放变量*/
    $num2 = 10;
    unset($num2);
    if(isset($num2)){
        echo"num2被定义了";
    }else{
        echo"num2没有被定义";
    }
echo"<br>";
    /*empty
     * 判断是否为空*/
    $num3 = ‘ ‘;
    if(empty($num3)){
        echo"num3是空";
    }else{
        echo"num不是空";
    }

    /*变量名大小写敏感*/
    $name = ‘zhangsan‘;
    $NAME = ‘lisi‘;
    echo$name;
    echo"<br>";
    echo$NAME;
echo"<br>";

    /*单引号里面全是字符串
     * 双引号可解析变量*/
    $net = "lemon";
    $age = 18;
    /*双引号套单引号要加转移符*/
    $string = "今天天气不错{$age}岁的{$net}出去\"玩\"了";
    /*单引号套单引号要加转移符*/
    $string2 = ‘今天天气不错{$age}岁的{$net}出\‘去\‘玩了‘;
    echo$string;
echo"<br>";
    echo$string2;

echo"<br>";
    /*两种拼接字符串的方法*/
    $string4 = ‘今天天气晴朗‘;
    $string5 = ‘我们出去玩吧‘;
    $result = "{$string4}{$string5}";
    echo$result;
echo"<br>";
    echo$string4.$string5;

PHP-day01


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