PHP学习笔记(一)
PHP的脚本以结束。在支持简写的服务器上，可以使用 ?>来开始和结束脚本块。为了兼容性，尽量使用标准形式。PHP通常会包含HTML标签，就像HTML文件，以及一些PHP脚本代码。下面是一段简单的PHP代码，
<html> <?php echo "Hello World!" ?> </html>
有两种通过PHP来输出文本的基础指令，echo和print.
PHP中所有变量都是以$符号开始的。
设置变量的正确方法是：
$var_name = value;
PHP是一门松散类型的语言，在PHP中，不需要在设置变量之前声明该变量。
根据变量被设置的方式，PHP会自动地把变量转换为正确的数据类型。
在PHP中，变量会在使用时被自动声明。
在PHP中，只有一个字符串运算符。
并置运算符(.)用于把两个字符串连接起来。
如：
$txt1="Hello World";
$txt2="nihao";
echo $txt1 . " " . $txt2;
?>
以上代码输出
Hello World nihao
strpos() 函数用于在字符串内检索一段字符串或一个字符。
如果在字符串中找到匹配，该函数会返回第一个匹配的位置。如果未找到匹配，则返回 FALSE。
如：
<?php
echo strpos("Hello world!","world");
?>
返回的是6.（从0开始）
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