14 problems that most make PHP beginners headache
Variable get,post,session cannot be passed between "1" pages in the latest version of PHP the automatic global variable is turned off, so the submission from the previous page must be obtained by using $_get[' foo '],$ _post[' foo '],$_session[' Foo '] to get. Of course, you can also modify the automatic global variable to open (php.ini changed to Register_globals = ON), and it is better to force yourself to be familiar with the new wording, considering compatibility.
"2" Win32 under Apache2 there is an error in passing the Chinese parameter with the Get method:
test.php?a= Hello &b= You
Passing parameters can cause an internal error
Solution: "Test.php?a=". UrlEncode (Hello). " &b= ". UrlEncode (you are also good)
.............
The session under "3" Win32 does not work properly
php.ini default Session.save_path =/tmp
This is obviously the configuration under Linux, Win32 PHP can not read and write session file cause session can not be used, it can be changed to an absolute path, such as Session.save_path = C:windows emp
"4" displays an error message
When PHP.ini's display_errors = on and error_reporting = E_all, all errors and prompts are displayed, and it is best to turn on the error when debugging, if you use the previous PHP error message is mostly about undefined variables. Variables are prompted before they are assigned, and the solution is to detect or mask them.
For example, $foo can be displayed, if (Isset ($foo)) echo $foo or echo @ $foo
"5" Win32 Mail () cannot send e-mail
In Linux, CONFIGURED SendMail can be sent, under Win32 need to invoke the SMTP server to send e-mail, modify the php.ini SMTP = IP//ip is without authentication function of the SMTP server (hard to find online)
The best solution for PHP to send mail is to send it directly to the other email server without forwarding the server.
"6" first installed MySQL if you do not set a password, you should use the update mysql.user set password= "YourPassword" where user= "root" to modify the password
"7" header already sent
This error usually occurs when you use the header, he may be several reasons: 1, you are Pring or Echo 2 before using header. You have a blank line 3 in front of your current file. You may include a file with a blank line at the end of the file, or an error in the output.
No change after "8" change php.ini
Restart the Web server, such as Iis,apache, and so on, before applying the latest settings.
"9" PHP installed on 2003 (ISAPI installation method kindly advise)
PHP4 's php4isapi.dll seems to be in conflict with 2003 and can only be installed in CGI mode
Step one, first www.php.net under a setup program, I was pretending to be: Php-4.2.3-installer.exe, you can also go to find the latest version in the installation php-4.2.3- Installer.exe before you make sure your IIS6.0 is started and can be accessed. Once installed,--> the application configuration on the default Web site.
Step Two: Click the Web Services extension--> to create a new Web service extension.
Step three: Extension-->php, and then add
Step four: Find the path of php.exe add up.
Step five: Be sure.
Step Six: Select the service Extensions for PHP and click Allow.
"10" Sometimes the SQL statement does not work, the database operation failed, the easiest way to debug, echo SQL, look at the value of the variable can be obtained.
The difference between "11" include and require
There is not much difference between the two, if the file you want to include does not exist, include prompts notice, and then proceed to the following statement, require prompt for fatal error and exit.
As far as I have tested, they are all included in the Win32 platform, so it is best not to have include or require statements in the included files, which can cause directory clutter. Perhaps *nux under different circumstances, not yet tested.
If a file does not want to be included multiple times, it can be read using include_once or require_once## to write document data.
function R ($file _name) {
$filenum = @fopen ($file _name, "R");
@flock ($filenum, lock_sh);
$file _data= @fread ($filenum, FileSize ($file _name));
@fclose ($filenum);
return $file _data;
}
function W ($file _name, $data, $method = "W") {
$filenum = @fopen ($file _name, $method);
Flock ($filenum, LOCK_EX);
$file _data=fwrite ($filenum, $data);
Fclose ($filenum);
return $file _data;
}
The difference between "12" isset () and Empty ()
Both are used for test variables, but Isset () is the test variable is assigned, and empty () is to test whether a variable that has already been assigned is empty.
If a variable is not assigned to the reference in PHP is allowed, but there will be notice hint, if a variable is assigned null value, $foo = "" or $foo=0 or $foo =false, then empty ($foo) return True, Isset ($foo) also return True, This means that the null value does not unregister a variable.
To unregister a variable, you can use Unset ($foo) or $foo=null
"13" MySQL query statement contains a keyword
PHP query MySQL, sometimes MySQL table name or column name will have a keyword, this time the query will have errors. For example, the table name is an order, the query will be an error, the simple way is the SQL statement table name or column name plus ' [tab] to distinguish between, such as SELECT * from ' order '
"14" Method of uploading multiple files at once via HTTP protocol
There are two ideas, which are two implementations of the same method. Specific procedures also need to design their own.
1. Set up multiple file input boxes in form and name them by array, as follows:
<form action= "" method=post>
<input Type=file name=usefile[]>
<input Type=file name=usefile[]>
<input Type=file name=usefile[]>
</form>
In this way, the following tests are done on the server side:
echo "<pre>";
Print_r ($_files);
echo "</pre>";
2, in the form to set up multiple file input box, but the name is different, as follows:
<form action= "" method=post>
<input Type=file name=usefile_a>
<input Type=file name=usefile_b>
<input Type=file name=usefile_c>
</form>
Do the same test on the server side:
echo "<pre>";
Print_r ($_files);
echo "</pre>";
