PHP Section FAQ Summary _php

1: Why don't I get the variable

I post data on one page to another page name, why is the output $name not get any value?

In later versions of PHP4.2, Register_global defaults to OFF. To get a variable submitted from another page:

Method One: Find the Register_global in php.ini and set it to on.
Method Two: Put this extract ($_post) in front of the receiving page, extract ($_get);(Note Extract ($_session) must have Session_Start ()).
Method Three: A read variable $a=$_get["a"]; $b =$_post["B"), this method is troublesome, but relatively safe.

2: Debug Your Program

At run time you must know why a variable is a value. I did this by creating a document debug.php, which reads as follows:

PHP Code:

　　 Ob_start ();
Session_Start ();
Echo "

";
Echo "This page has the _get variable:";
Print_r ($_get);
Echo "This page has the _post variable:";
Print_r ($_post);
Echo "This page has the _cookie variable:";
Print_r ($_cookie);
Echo "This page has the _session variable:";
Print_r ($_session);
Echo "

";
?>

Then set in php.ini: include_path = "c:/php", and put debug.php in this folder, in the future you can include this file in each page, view the resulting variable name and value.

3: How to use Session

In the case of a session, the function session_start () must be called before, and the value for the session is simple, such as:

PHP Code:

　　 Session_Start ();
$Name = "This is a session example";
Session_register ("Name");//note, do not write: Session_register ("$Name");
Echo $_session["Name"];
After the $_session["Name"] is "This is a SESSION example"
?>

After php4.2, you can pay a value for the session directly:

PHP Code:

　　 Session_Start ();
$_session["Name"]= "value";
?>

The cancellation session can be done like this:

PHP code session_start ();
Session_unset ();
Session_destroy ();
?>

Cancel a Session variable above php4.2 there is a bug.

Attention:

1: cannot have any output before calling Session_Start (). For example, the following is an error.
1 rows
2 lines 3 rows session_start ();//before the first line already has output
4 lines .....
5 Row?>

Tip 1:

Anything that appears "... headers already sent ..." is the output of information to the browser before Session_Start (). Remove the output to normal, (the cookie will also appear this error, the same reason)

Tip 2:

If your session_start () is placed in a looping statement and it is difficult to determine where to export the information to the browser before, you can use this method: 1 rows
........ Here is your program ...

2: What is wrong with this

Warning:session_start (): Open (/tmp\sess_7d190aa36b4c5ec13a5c1649cc2da23f, O_RDWR) failed: ....
Because you did not specify a path to store the session file.

Workaround:
(1) Set up folder TMP on C disk
(2) Open php.ini, find Session.save_path, change to Session.save_path= "C:/tmp"

4: Why do I transfer a variable to another page, only the first half of it, and all the ones that start with a space are lost

　　
PHP Code:

　　 $Var = "Hello php";//modified to $var= "Hello php"; try to get what results
$post = "receive.php?" Name= ". $Var;
Header ("Location: $post");
?>

Content of receive.php:

PHP Code:

　　 Echo "

";
Echo $_get["Name"];
Echo "

";
?>

The correct method is:

PHP Code:

　　 $Var = "Hello php";
$post = "receive.php?" Name= ". UrlEncode ($Var);
Header ("Location: $post");
?>

In the Receive page you do not need to use UrlDecode (), the variable is automatically encoded.

5: How to intercept the specified length of Chinese characters without appearing to end with "?>", Beyond the section with "..." instead

In general, the variables to be intercepted from MySQL, first of all to ensure that the field length is long enough, usually char (200), you can maintain 100 characters, including punctuation.

PHP Code:

　　 $str = "This character is very long, ^_^";
$Short _str=showshort ($STR, 4);//intercept the first 4 characters, the result is: this character ...
Echo "$Short _str";
Function csubstr ($str, $start, $len)
{
$strlen =strlen ($STR);
$clen = 0;
for ($i =0; $i < $strlen; $i, $clen)
{
if ($clen >= $start $len)
Break
if (Ord (substr ($str, $i, 1)) >0xa0)
{
if ($clen >= $start)
$tmpstr. =substr ($str, $i, 2);
$i;
}
Else
{
if ($clen >= $start)
$tmpstr. =substr ($str, $i, 1);
}
}

return $tmpstr;
}
Function Showshort ($STR, $len)
{
$tempstr = csubstr ($str, 0, $len);
if ($str <> $tempstr)
$tempstr. = "..."; To what end, modify here can be.

return $tempstr;
}

6: Standardize your SQL statements

In the table, precede the field with "'" so that there is no error due to misuse of the keyword,
Of course I do not recommend you to use keywords.

For example
$SQL = "INSERT into ' xltxlm ' (' Author ', ' title ', ' id ', ' content ', ' date ')

ValueS (' xltxlm ', ' use ', 1, ' criterion your SQL string ', ' 2003-07-11 00:00:00 ') "

"'" How to input? Above the TAB key.

7: How to make html/php format strings not interpreted, but displayed as-is

PHP Code:

　　 $str = "

Php

";
Echo "was explained:". $str. "
After treatment: ";
Echo htmlentities (NL2BR ($STR));
?>

8: How to get the value of the variable outside the function in the function

PHP Code:

　　 $a = "PHP";
Foo ();
Function foo ()
{
Global $a;//delete here to see what the results
Echo "$a";
}
?>

9: How do I know what functions the system supports by default

PHP Code:

　　 $arr = Get_defined_functions ();
Function php () {
}
echo "

Echo "shows all the functions supported by the system, and the custom function php\n";

echo "

";
?>

10: How to compare two dates for a few days

PHP Code:

　　 $Date _1= "2003-7-15";//can also be: $Date _1= "2003-6-25 23:29:14";
$Date _2= "1982-10-1";
$Date _list_1=explode ("-", $Date _1);
$Date _list_2=explode ("-", $Date _2);
$d 1=mktime (0,0,0, $Date _list_1[1], $Date _list_1[2], $Date _list_1[0]);
$d 2=mktime (0,0,0, $Date _list_2[1], $Date _list_2[2], $Date _list_2[0]);
$Days =round (($d 1-$d 2)/3600/24);
Echo "I have studied $Days days ^_^";
?>

11: Why did I upgrade PHP, the original program appears full screen notice:undefined variable:

This is the warning, because the variable is undefined.
Open PHP.ini, find the bottom error_reporting, modify to Error_reporting = E_all & ~e_notice

For parse Error Error
Error_reporting (0) cannot be closed.
If you want to turn off any error prompts, open php.ini, locate display_errors, set to Display_errors = off. No future errors will be prompted.

Then what is error_reporting?

12: I want to add a file to the top of each file and the last. But one adds a lot of trouble

1: Open php.ini file
Set include_path= "C:"

2: Write two files
Auto_prepend_file.php and auto_append_file.php are saved in the C drive and they will automatically be attached to the head and tail of each PHP file.

3: Found in php.ini:
Automatically add files before or after any PHP document.
Auto_prepend_file = auto_prepend_file.php; attached to the head
Auto_append_file = auto_append_file.php; attached to the tail

After you each PHP file is equivalent to

PHP code

　　 Include "auto_prepend_file.php";

...//This is your program.

　　
Include "auto_append_file.php";
?>

13: How to upload files using PHP

PHP Code:

　　
Uploading a file form

　　 $upload _file=$_files[' upload_file ' [' tmp_name '];
$upload _file_name=$_files[' upload_file ' [' name '];

if ($upload _file) {
$file _size_max = 1000*1000;//1M limit file upload maximum capacity (bytes)
$store _dir = "d:/";//storage location of uploaded files
$accept _overwrite = 1;//allows overwriting of the same file
Check File size
if ($upload _file_size > $file _size_max) {
echo "Sorry, your file size is greater than the provision";
Exit
}

Check read and write files
if (file_exists ($store _dir. $upload _file_name) && $accept _overwrite) {
Echo "file with the same file name exists";
Exit
}

Copy files to the specified directory
if (!move_uploaded_file ($upload _file, $store _dir. $upload _file_name)) {
echo "Failed to copy file";
Exit
}

}

Echo "

You uploaded the file: ";
echo $_files[' upload_file ' [' name '];
echo "
";
The original name of the client machine file.

Echo "file has a MIME type of:";
echo $_files[' upload_file ' [' type '];
The MIME type of the file requires the browser to provide support for that information, such as "Image/gif".
echo "
";

Echo "Upload file size:";
echo $_files[' upload_file ' [' Size '];
The size of the uploaded file, in bytes.
echo "
";

Echo "file was temporarily stored as:" After uploading;
echo $_files[' upload_file ' [' tmp_name '];
Temporary file names stored on the server after the files have been uploaded.
echo "
";

$Erroe =$_files[' upload_file ' [' Error '];
Switch ($Erroe) {
Case 0:
Echo "Upload success"; Break
Case 1:
Echo "uploaded a file that exceeds the value of the Upload_max_filesize option limit in php.ini."; Break
Case 2:
Echo "The size of the uploaded file exceeds the value specified by the Max_file_size option in the HTML form.　　"; Break
Case 3:
Echo "file is only partially uploaded";
Case 4:
Echo "No files were uploaded";
}
?>

14: How to configure the GD library

Here's my configuration process
1: Use DOS command (can also manually, copy all DLL files in DLLs folder to system32 directory) copy C:\php\dlls\*.dll c:\windows\system32\
2: Open php.ini
Set extension_dir = "c:/php/extensions/";
3:
Extension=php_gd2.dll, remove the comma in front of the extension, and if there is no php_gd2.dll,php_gd.dll, ensure that the file does exist C:/php/extensions/php_gd2.dll
4: Run the following program to test

PHP Code:

　　 Ob_end_flush ();
Note that you cannot output any information to the browser before, and be aware that Auto_prepend_file is set.
Header ("Content-type:image/png");
$im = @imagecreate (200, 100)
Or Die ("Cannot create image");
$background _color = imagecolorallocate ($im, 0, 0, 0);
$text _color = imagecolorallocate ($im, 230, 140, 150);
Imagestring ($im, 3, +, "A simple Text String", $text _color);
Imagepng ($im);
?>

15: What is the UBB code

UBB code is a variant of HTML, is Ultimate Bulletin Board (a foreign BBS program, there are many places in the domestic use of this program) a special tag. You can use Ubbcode even if you're forbidden to use HTML? To achieve. Maybe you'd rather use Ubbcode? Instead of HTML, even if the forum allows HTML, it is safer to use less code.

Q3boy's UBB has an example, you can run the test directly

　　
16: I want to modify the MySQL user, password

The first thing to declare is that in most cases, MySQL is required to have root privileges in MySQL,
So the general user cannot change the password unless the administrator is requested.

Method One
Using phpMyAdmin, this is the simplest, modify the MySQL library's user table,
But don't forget to use the password function.

Method Two
Using Mysqladmin, this is a special case of the preceding declaration.
Mysqladmin-u root-p Password mypasswd
After entering this command, you need to enter the root's original password, then the root password will be changed to MYPASSWD.
Change the root of the command to your username, and you can change your own password.
Of course if your mysqladmin is not connected to MySQL server, or you have no way to execute mysqladmin,
Then this method is ineffective.
And mysqladmin can't erase the password.

The following methods are used at the MySQL prompt and must have root privileges for MySQL:
Method Three
Mysql> INSERT into Mysql.user (Host,user,password)
ValueS ('% ', ' Jeffrey ', PASSWORD (' biscuit '));
Mysql> FLUSH Privileges
Specifically, this is the addition of a user named Jeffrey, with a password of biscuit.
There is this example in the MySQL Chinese reference manual, so I wrote it out.
Note that you want to use the password function, and then you also use the flush privileges.

Method Four
As with method Three, just use the Replace statement
Mysql> REPLACE into Mysql.user (Host,user,password)
ValueS ('% ', ' Jeffrey ', PASSWORD (' biscuit '));
Mysql> FLUSH Privileges

Method Five
Using the Set Password statement,
Mysql> SET PASSWORD for jeffrey@ "%" = PASSWORD (' biscuit ');
You must also use the password () function,
However, you do not need to use flush privileges.

Method Six
Use Grant ... Identified by statement
Mysql> GRANT USAGE on * * to jeffrey@ "%" identified by ' biscuit ';
Here the password () function is unnecessary and does not require the use of flush privileges.

Note: PASSWORD () [NOT] Execute password encryption in the same way that the UNIX password is encrypted.

　　
17: I want to know which website he is connecting to this page

PHP Code:

　　 The output must be entered through a super connection
Echo $_server[' Http_referer '];
?>

18: Data put into the database and taken out to show what needs to be noted on the page

When in storage
$str =addslashes ($STR);
$sql = "INSERT INTO ' tab ' (' Content ') VALUES (' $str ')";
When you are out of the library
$str =stripslashes ($STR);
When displayed
$str =htmlspecialchars (NL2BR ($STR));

19: How to read the current address bar information

PHP Code:

　　 $s = "http://{$_server[' http_host ']}:{$_server[" server_port "]}{$_server[' Script_name ']}";
$se = ";
foreach ($_get as $key = = $value) {
$se. = $key. " = ". $value." & ";
}
$se =preg_replace ("/(. *) &$/", "$", $se);
$se? $se = "?". $se: "";
echo $s. "? $se ";
?>

20: I click on the Back button, why did the thing before fill disappear

This is because you used the session.
Workaround:

PHP Code:

　　 Session_cache_limiter (' Private, must-revalidate ');
Session_Start ();
...........
..........
?>

21: How to show the IP address in the picture

PHP Code:

　　 Header ("Content-type:image/png");
$img = Imagecreate (180,50);
$ip = $_server[' remote_addr ');
Imagecolortransparent ($img, $bgcolor);
$bgColor = Imagecolorallocate ($img, 0X2C,0X6D,0XAF); Background color
$shadow = Imagecolorallocate ($img, 250,0,0); Shadow color
$textColor = Imagecolorallocate ($img, Oxff,oxff,oxff); Font Color
Imagettftext ($img, 10,0,78,30, $shadow, "D:/windows/fonts/tahoma.ttf", $IP); Show background
Imagettftext ($img, 10,0,25,28, $textColor, "D:/windows/fonts/tahoma.ttf", "Your IP is". $ip); Display IP
Imagepng ($IMG);
Imagecreatefrompng ($IMG);
Imagedestroy ($IMG);
?>

22: How to get the real IP of the user

PHP Code:

　　 function Iptype1 () {
if (getenv ("Http_client_ip")) {
Return getenv ("Http_client_ip");
}
else {
return "None";
}
}
function Iptype2 () {
if (getenv ("Http_x_forwarded_for")) {
Return getenv ("Http_x_forwarded_for");
}
else {
return "None";
}
}
function Iptype3 () {
if (getenv ("REMOTE_ADDR")) {
Return getenv ("REMOTE_ADDR");
}
else {
return "None";
}
}
function IP () {
$ip 1 = iptype1 ();
$ip 2 = iptype2 ();
$ip 3 = Iptype3 ();
if (Isset ($ip 1) && $ip 1! = "None" && $ip 1! = "Unknown") {
return $IP 1;
}
ElseIf (Isset ($ip 2) && $ip 2! = "None" && $ip 2! = "Unknown") {
return $IP 2;
}
ElseIf (Isset ($ip 3) && $ip 3! = "None" && $ip 3! = "Unknown") {
return $IP 3;
}
else {
return "None";
}
}

Echo IP ();
?>

23: How to read all records from the database in three days

First, there is a datetime field in the table to record the time,
Formatted as ' 2003-7-15 16:50:00 '

SELECT * from ' xltxlm ' WHERE to_days (now ())-to_days (' Date ') <= 3;

24: How to remotely link MySQL database

In the MySQL table for adding users, there is a host field, modified to "%", or an IP address that allows the connection, so that you can call it remotely.

$link =mysql_connect ("192.168.1.80:3306", "Root", "" ");

25: After using Apache, the main page appears garbled

　　
Method One:
Adddefaultcharset iso-8859-1 change to adddefaultcharset off

Method Two:
Adddefaultcharset GB2312

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