Reasons and solutions for blank pages in php_PHP tutorial

A blank page in PHP programming may be caused by the following reasons:
1. Logic errors
Logic errors are the most difficult to eliminate. On the surface, maybe the code is legal, yes It's formal, but it doesn't work as expected. Why? Maybe the writer didn't think comprehensively enough. After all, people are people and computers are computers. It is impossible for computers to run scripts completely according to human ideas. Here, I will tell you a better debugging method, which is to use the comment symbols "/* */" to comment out some code and observe the operation. If you want to completely eliminate logical errors, you won't be able to do it without patience, so you have to calm down and don't be anxious.
2. The behavior is undefined
Look at the following code:
$action = $_GET['id'];
if($action == '')
$action = 1;
if($action == 1) {
echo("/$action's value is 1");
} else if($action == 2) {
echo("/$action's value is 2");
}
?>
This code is very clear to everyone, that is, if the $action variable is empty, set it to 1, and then Determine the value of the $action variable and make different events. Of course, what will PHP do if $action is neither equal to 1 nor equal to 2? ? -- will do nothing, so a blank page will be produced. Once you know the cause, the solution is easy. The solution to this problem is very simple. Just add an else after the if module and print some information.
3. Grammar Error
You may ask, if there is a grammatical error, there will usually be an error message. Why is it blank? Of course, this is just an individual phenomenon. In some homepage spaces (such as the free space of China Ju.com), if you write PHP with grammatical errors, it will not give any prompts. The solution is also easy, just test it locally before uploading the file to find out the wrong code and correct it. (www.bkjia.com)
4. Abuse of the error suppressor @
The error suppressor "@" is often used where errors may occur, but if the suppressor is used too much or at the wrong time, it may To avoid causing blank spaces, let’s take a look at the following two PHP scripts:
test1.php
@include("test2.php");
echo($var) ;
?>
test2.php
$var = "Hi" //There is an error in this line of code, there is no semicolon
$var1 = "Hello" / /Same as above
?>
Run test1 to see, the result is a blank page. Correction is also very simple. You can remove the suppressor in front of the include function, or correct the error in the test2.php file.

http://www.bkjia.com/PHPjc/371501.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/371501.htmlTechArticleBlank pages appearing in PHP programming may be caused by the following reasons: 1. Logic errors Logic errors are The most difficult thing to rule out is that on the surface, maybe the code is legal and formal...