在PHP中使用html和javascript标签

Question

I am confused about using single and double quotes and back slash while using java script and html tags in php can any one please clarify i googled it but still not clear about it. i am confused for this small thing.i am new to programming - here is my code

 <?php
if(isset($_GET['id'])) {
echo '<div id="d2">';
include "test2.php";
 echo '</div>'; }
 else
 { 
  echo '<div id="d1">';
 include "insert.php";
 print "<script type=javascript>"
 print "document.getEelementById('alertdiv1').innerHTML='hi' ;"
 print "</script>"
echo '</div>';
     }
?>

Answer 1

In PHP, you can enclose a string in either single quotes or double quotes. Both are valid:

$var = "this is a string";
$var2 = 'this is also a string';

The main difference is that if your string contains a variable, and you want the variable content to be treated as part of the string, you need to use double quotes:

echo "$var which I made";

will return:

this is a string which I made

When you are manipulating html, css and JavaScript strings, you need to make sure that you don't accidentally close your PHP string. For example:

echo "<h1 class='myheading'>Heading Text</h1>";

Notice how I used double quotes to enclose my string? Because I did that, I was able to use single quotes in the html, without escaping them.

If I'd wanted to use double quotes in my string, I would have had to escape them, like this:

echo "<h1 class=\"myheading\">Heading Text</h1>";

The \ tells PHP that the double quote which immediately follows is to be treated as a literal, and not used to terminate the string.