php 学习

<?php
    $txt = 'Hello world';
    echo $txt;
?>
<br/>
字符串连接(.)
<br/>
echo 'Hello world'. "" . '1234'  输出： 
<?php
    $txt1 = 'Hello world';
    $txt2 = '1234';
    echo $txt1. "" . $txt2;
?>
<br/>
strlen 函数用法 echo strlen('Hello world') 输出：
<?php
    $txt = 'Hello world';
    echo strlen($txt);
?>
<br/>
strpos() 在字符串中找到匹配，该函数会返回第一个匹配的位置  输出：
<?php
    echo strpos('Heldddlo world', 'world');
?>
<?php
  $x = 5; $y = 0106;
    echo  $x = $x.$y;
   
    ?>
    <br/>
<?
    echo $y;
?>
<br/>
if .... elseif
<?
    $d = date("D");
    if ($d == "Wed")
        echo "Have a nice weekend!<br/>";
    else
        echo "Have a nice day!";
?>
<br/>
<?php
switch ($x)
{
case 1:
  echo "Number 1";
  break;
case 2:
  echo "Number 2";
  break;
case 3:
  echo "Number 3";
  break;
default:
  echo "No number between 1 and 3";
}
?>
<br/>
<?
    $ages = array("Peter"=>32, "Quagmire"=>30, "Joe"=>34);
    echo "Peter is ". $ages['Peter']. "years old.";
?>
<br/>
<?
$families = array
(
  "Griffin"=>array
  (
  "Peter",
  "Lois",
  "Megan"
  ),
  "Quagmire"=>array
  (
  "Glenn"
  ),
  "Brown&quo