[php learning 2] Basic grammar exercises 1-PHP Tutorial-php.cn

[php learning 2] Basic grammar exercises 1

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Release： 2016-07-28 08:27:57

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>First Php</title>
</head>
<body>
<h1>三好少年</h1>
<?php
/*基本语法练习
*1,定义变量必须加$,但不用写类型.这就导致了定义和赋值是一样的语句了.
*/
$x = 5;
$y = 10;
function Test(){
    global $x , $y;/*访问全局变量必须加GLOBAL*/
    static $z = 0;/*静态局部变量*/
    $y = $y + $z;
    $z++;
}
Test();
Test();
echo $y,&#39;<br>';//11

/*
 * 1,echo没有返回值,可以输出多个字符串,逗号隔开~
 * 2,Print总返回1,只能输出一个字符串~
 * 3,单引号只能输出字符串,双引号能输出变量~
 * 4,var_dump这个犀利啊,能监测变量类型,并输出值.
 * 5,数组元素可以不同类型,这个语法也是没谁了.
*/
$cars = array("Volvo","BMW","TOYOTA",5);
echo "字符串1","字符串2",'字符串3';
echo '<h2>PHP IS Fun</h2>';//还能输出标签~
echo "$cars[0]<br>";
print("print只能一个字符串<br>");
print("print也能输出标签<h2>print标签</h2>");
var_dump($cars); print '<br>';

/*
 * 1,常量的定义真不怎么样,默认区分大小写,想不区分的话,最后参数为False;
 * 2,print(china_display + constInt + '<br>');这个有错误,但能运行,只显示800;看来这个编译器不是很严格.~
 * 3,常量默认全局的,函数调用的话不用Global修饰;
 * */
define("china_display","中华人民共和国");
define("constInt",800);
echo china_display,constInt,'<br>';
function TestConst($a){
    echo china_display, $a, '<br>';
}
TestConst("伟大");

/*
 * 1,两个字符串链接有个叫"并置运算符"用.标示,链接两个字符串.~
 * 2,strlen对于汉字的输出是n*3,不是n*2;
*/
$txt1 = '字符串第一部分';
$txt2 = '字符串第二部分';
print $txt1 . $txt2 .'<br>';
echo 'abc 长度',strlen("abc"),";","你好么 长度",strlen("你好么"), "<br>";
echo 'abc b的位置',strpos("abc","b"),";","你好么 好的位置",strpos("你好么","好") ,"<br>";

/*
 * 1,比较运算符中,==和===是两码事,==纯粹的比较,====加上了类型的判断.
 * 2,echo false什么也不输出;
 * 3,isset()如果变量未设置或者为NULL,则返回False,否则True;挺重要的函数啊~;
 * 4,empty()如果变量不存在或其值为""、0、"0"、NULL、、FALSE、array()、var $var; 以及没有任何属性的对象，则返回True,否则False;
 * */
$int100 = 100;
$str100 = '100';
function BoolToStr($A){
   if ($A === true){
       return "True";
   }
   else{
        return "False";
   }
}
echo BoolToStr($int100 == $str100) , ",", BoolToStr($int100 === $str100),"<br>";//true,false
$ussername = true?"0":"hello";
print BoolToStr(isset($ussername)) . '<br>';//True
print BoolToStr(empty($ussername)) . '<br>';//True

/*
 * 1,switch也支持字符串;
 * 2,没有Default也不抱错.
 * */
$favcolor="red";
switch ($favcolor) {
    case "red":
        echo "你喜欢的颜色是红色!";
        break;
    case "blue":
        echo "你喜欢的颜色是蓝色!";
        break;
    case "green":
        echo "你喜欢的颜色是绿色!";
        break;
    default:
        echo "你喜欢的颜色不是 红, 蓝, 或绿色!";
}

/*
 * 1,count能计算出数组长度,这中写法有点LOW,早晚写个全局类来替代它.
 * 2,Count对字符串无效,结果为1;
 * 3,关联数组的类型也是混着都可以.前面是索引,后面是值,所以这类数组只能Foreach遍历;
 * */
echo "Cars数量:",count($cars),'<br>';//4
echo count("aaaaddd"),'<br>';//1
for ($x = 0; $x < count($cars); $x ++) {
    echo $cars[$x], '<br>';
}
foreach($cars as $x){
    echo $x, '<br>';
}
$ages = array('梅西'=>29, "C罗"=>'31',5=>8);
foreach($ages as $x => $x_value){
    echo "name:",$x,"age:",$x_value,'<br>';
}

echo $ages["C罗"];
?>
</body>
</html>

<?php
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