PHP Beginner FAQs

Top 14 Questions for beginners with a headache

Management reminder: This post is Haowubai perform a sticky action (2009-04-16) "1" Polygon cannot pass the variable get,post,session in the latest PHP version, the auto global variable is closed, so you have to get the argument from the previous side to use $_get[' Foo '],$_post[' foo '],$_session[' foo ' to get. Of course, you can also modify the automatic global variable to ON (php. ini to register_globals = on); It is better to force yourself to be familiar with the new wording, considering compatibility.

"2" win under Apache using the Get method to pass Chinese parameters will be an error:

test.php a= Hello &b= you.

Passing parameters can cause an internal error
　
Workaround: "test.php a=". UrlEncode (Hello). " &b= ". UrlEncode (you're good too)

"3" The session under win does not work properly

PHP. ini default Session.save_path =/tmp

This is obviously the configuration under Linux, win PHP cannot read and write the session file resulting in the session can not be used, change it to an absolute path, such as Session.save_path = C:windows emp

"4" Displays error message

When php. ini display_errors = on and error_reporting = E_all, all errors and hints are displayed, preferably open for error correction when debugging, and if you use the previous PHP notation, most of the error messages are about undefined variables. Variables are called before they are assigned, and the solution is to detect or block.

For example, $foo can be displayed, if (Isset ($foo)) echo $foo or echo @ $foo

"5" Win under Mail () cannot send e-mail

SendMail configured under Linux can be sent, under win need to call the SMTP server to send e-mail, modify the php. ini = IP//IP is an SMTP server without authentication (hard to find online)

PHP the best way to send mail is to send the socket directly to the other email server instead of forwarding the server.

"6" first installed MySQL if you do not have a password set, 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, and he may be a couple of reasons: you pring or echo before you use the header. You have a blank line in front of your current file. You may include a file with a blank line or output at the end of the file.

"8" does not change after PHP. ini

Restart the Web server, such as Iis,apache and so on, before the latest settings are applied.

"9" PHP is installed on 00 (ISAPI installation method Request Master advice)

PHP php Isapi.dll seems to be in conflict with 00, can only be installed in CGI mode

Step one, first www.php. NET under a setup program, I am Loaded is: PHP-.. -installer.exe, you can also go to the latest version when installing PHP-.. -installer.exe before you make sure your IIS6.0 is up and able to access it. After installation,--> the application configuration on the default Web site.

Step Two: Click Web Service Extension--> to create a new Web service extension.

Step three: Extension-->php, and then add

Step four: Find the path to the PHP. exe to add it up.

Step five: OK, yes!
　
Step six: Select PHP's service extensions, then click Allow.

"10" Sometimes SQL statements do not work, the database operation failed, the simplest debugging method, echo that SQL, look at the value of the variable can get No.

The difference between the "11" include and the Require

There is not much difference between the two, if the file to be included does not exist, include prompts notice, and then proceeds to execute the following statement, require prompts for a fatal error and exits.

According to my test, the win platform they are first included after execution, so the included file is best not have include or require statements, which will cause the directory confusion. Perhaps *nux under different circumstances, not yet tested.

If a file does not want to be included multiple times can be read using include_once or require_once##, write the 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 test variables, but Isset () is the test variable is assigned, and empty () is the test of whether a variable that has 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 a null value, $foo = "" or $foo=0 or $foo =false, then empty ($foo) return True, Isset ($foo) also return True, This means that a null value does not unregister a variable.
　
To unregister a variable, you can use Unset ($foo) or $foo=null

The "13" MySQL query statement contains a keyword

When PHP queries MySQL, sometimes MySQL table name or column name will have a keyword, this time the query will be error. For example, the table name is Order, the query will be error, the simple way is the SQL statement table name or column name plus ' [Tab key] to distinguish, such as SELECT * from ' order '

"14" Method of uploading multiple files one time via HTTP protocol

There are two ideas that are two implementations of the same method. Specific procedures also need to design their own.

, set multiple file input boxes in the form, name their names with an array, as follows:

In this way, the following tests are done on the server side:

echo "

";
Print_r ($_files);
echo "

";
, set multiple file input boxes in the form, but with different names, as follows:

Do the same test on the server side:

echo "

";
Print_r ($_files);
echo "

";

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