Shulou(Shulou.com)06/03 Report--

This article mainly talks about "what are the methods of php error handling". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn what are the methods of php error handling.

1: why can't I get the variable

When I POST data name from one page to another, why don't I get any value when I output $name?

In later versions of PHP4.2, register_ Global defaults to off

To get a variable submitted from another page:

Method 1: find register_global in PHP.ini and set it to on.

Method 2: put the extract ($_ POST) at the front of the receiving web page; extract ($_ GET); (note that there must be Session_Start () before extract ($_ SESSION)).

Method 3: read the variables $a=$_GET ["a"]; $b=$_POST ["b"] one by one, which is troublesome but safe.

2: debug your program

You must know why a variable is valued at run time. I did this by creating a file debug.php with the following contents:

PHP code:--

The copy code is as follows:

Ob_Start ()

Session_Start ()

Echo ""

Echo "the _ GET variables obtained on this page are:"

Print_R ($_ GET)

Echo "the _ POST variables obtained on this page are:"

Print_R ($_ POST)

Echo "the _ COOKIE variables obtained on this page are:"

Print_R ($_ COOKIE)

Echo "the _ SESSION variables obtained on this page are:"

Print_R ($_ SESSION)

Echo ""

-

Then set include_path = "c:/php" in php.ini and put debug.php in this folder

Later, you can include this file in each page and view the variable name and value.

3: how to use session

Anything related to session must be called before the function session_start ().

Paying for session is simple, such as:

The copy code is as follows:

Session_start ()

$Name = "this is an example of Session"

Session_Register ("Name"); / / Note, do not write as: Session_Register ("$Name")

Echo $_ SESSION ["Name"]

/ / then $_ SESSION ["Name"] is "this is an example of Session"

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

The copy code is as follows:

Session_Start ()

$_ SESSION ["name"] = "value"

To cancel session, you can do this:

The copy code is as follows:

Session_start ()

Session_unset ()

Session_destroy ()

Cancel a session variable above php4.2 and BUG.

Note:

1: you cannot have any output until you call Session_Start (). For example, the following is wrong.

= =

1 Lin

2 lines [php]

Line 3 Session_Start (); / / already has output on the first line

Four lines.

5 lines [/ php]

= =

Tip 1:

Whenever ".headers already sent." appears, it outputs information to the browser before Session_Start ().

It is normal to get rid of the output (the same error will occur in COOKIE for the same reason)

Tip 2:

If your Session_Start () is in a loop statement, and it is difficult to determine where to output information to the browser before, you can use the following method:

1 line [php] Ob_Start (); [/ php]

. Here is your program.

2: what kind of mistake is this

Warning: session_start (): open (/ tmpsess_7d190aa36b4c5ec13a5c1649cc2da23f, O_RDWR) failed:....

Because you did not specify the path where the session file is stored.

Solution:

(1) create a folder tmp on disk c

(2) Open php.ini, find session.save_path, and change it to session.save_path= "c:/tmp".

4: why do I only get the first half of the variables when I send variables to another page, and lose all those that start with a space

The copy code is as follows:

$Var= "hello php"; / / change it to $Var= "hello php"; try to get something

$post= "receive.php?Name=". $Var

Header ("location:$post")

The content of receive.php:

The copy code is as follows:

Echo ""

Echo $_ GET ["Name"]

Echo ""

The correct way is:

The copy code is as follows:

$Var= "hello php"

$post= "receive.php?Name=" .urlencode ($Var)

Header ("location:$post")

You do not need to use Urldecode () on the receiving page, the variables are automatically encoded.

How to intercept Chinese characters of specified length without ending with "[/ php]" and the excess part with "..." Replace

Generally speaking, the variable to be intercepted comes from Mysql. The first step is to make sure that the length of that field is long enough, usually char (200), which can keep 100 Chinese characters, including punctuation.

The copy code is as follows:

$str= "this character is so long, ^ _ ^"

$Short_Str=showShort ($str,4); / / intercepts the first four Chinese characters, the result is: this character.

Echo "$Short_Str"

Function csubstr ($str,$start,$len)

{

$strlen=strlen ($str)

$clen=0

For ($iTunes, investors, startmakers)

Break

If (ord (substr ($str,$i,1)) > 0xa0)

{

If ($clen > = $start)

$tmpstr.=substr ($str,$i,2)

$iTunes +

}

Else

{

If ($clen > = $start)

$tmpstr.=substr ($str,$i,1)

}

}

Return $tmpstr

}

Function showShort ($str,$len)

{

$tempstr = csubstr ($str,0,$len)

If ($str$tempstr)

$tempstr. = "..."; / / what you want to end with, just modify it here.

Return $tempstr

}

6: standardize your SQL statements

Add "`" to the table and field so that there is no error due to the misuse of keywords.

Of course, I don't 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 criterion your sql string')"

How to enter "`"? Above the TAB key.

7: how to make a string in Html/PHP format not interpreted, but displayed as is

The copy code is as follows:

$str= "PHP"

Echo "explained:". $str. "

Processed: "

Echo htmlentities (nl2br ($str))

8: how to get the value of variables outside the function in the function

The copy code is as follows:

$a = "PHP"

Foo ()

Function foo ()

{

Global $a share / delete here to see what the result is.

Echo "$a"

}

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

The copy code is as follows:

$arr = get_defined_functions ()

Function php () {

}

Echo ""

Echo "all the functions supported by the system are shown here, and the custom function phpn"

Print_r ($arr)

Echo ""

10: how to compare the difference between two dates by a few days

The copy code is as follows:

$Date_1= "2003-7-15"; / / it 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)

$d1=mktime (0je 0je 0je jinx Datekeeper Lister1 [1], $Date_List_1 [2], $Date_List_1 [0])

$d2=mktime (0je 0je 0je jinx Datekeeper Lister2 [1], $Date_List_2 [2], $Date_List_2 [0])

$Days=round (($d1-$d2) / 3600lap24)

Echo "I've been fighting for $Days day ^ _ ^"

11: why after I upgraded PHP, the original program showed a full screen of Notice: Undefined variable:

This is a warning because the variable is not defined.

Open php.ini, find the lowest error_reporting, and change it 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 messages, open php.ini, find display_errors, and set it to display_errors = Off. Any future mistakes will not be prompted.

Then what is error_reporting?

12: I want to add a document to the front and end of each document. But it's troublesome to add one by one.

1: open the php.ini file

Set include_path= "c:"

2: write two files

Auto_prepend_file.php and auto_append_file.php are saved on disk C, and they are automatically attached to the header and tail of each php file.

3: find the following 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

In the future, each of your php files will be the equivalent of

The copy code is as follows:

Include "auto_prepend_file.php"

. / / here is your program

Include "auto_append_file.php"

13: how to upload files using PHP

The copy code is as follows:

Upload file form

Please select a file:

$upload_file=$_FILES ['upload_file'] [' tmp_name']

$upload_file_name=$_FILES ['upload_file'] [' name']

If ($upload_file) {

$file_size_max = 1000 upload 1000ram / 1m limit maximum file upload capacity (bytes)

$store_dir = "dvv /"; / / the storage location of the uploaded file

$accept_overwrite = 1 ram / whether the same file is allowed to be overwritten

/ / check file size

If ($upload_file_size > $file_size_max) {

Echo "Sorry, your file capacity is larger than the limit".

Exit

}

/ / check read and write files

If (file_exists ($store_dir. $upload_file_name) & &! $accept_overwrite) {

Echo "A file with the same file name"

Exit

}

/ / copy files to the specified directory

If (! move_uploaded_file ($upload_file,$store_dir.$upload_file_name)) {

Echo "failed to copy files"

Exit

}

}

Echo "

You uploaded the file: "

Echo $_ FILES ['upload_file'] [' name']

Echo "

"

/ / the original name of the client machine file.

The MIME type of the Echo "file is:"

Echo $_ FILES ['upload_file'] [' type']

/ / the MIME type of the file, which needs to be supported by the browser, such as "image/gif".

Echo "

"

Echo "upload file size:"

Echo $_ FILES ['upload_file'] [' size']

/ / the size of the uploaded file in bytes.

Echo "

"

Echo "the file is temporarily saved as:"

Echo $_ FILES ['upload_file'] [' tmp_name']

/ / the temporary file name stored on the server after the file is uploaded.

Echo "

"

$Erroe=$_FILES ['upload_file'] [' error']

Switch ($Erroe) {

Case 0:

Echo "uploaded successfully"; break

Case 1:

Echo "uploaded files exceed the limit of the upload_max_filesize option 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 "only part of the file was uploaded"; break

Case 4:

Echo "no files were uploaded"; break

}

14: how to configure the GD library

Here is my configuration process

1: use the dos command (or manually, copy all the dll files in the dlls folder to the system32 directory) copy c:phpdlls*.dll c:windowssystem32

2: open php.ini

Set extension_dir = "c:/php/extensions/"

3:

Extension=php_gd2.dll; removes the comma before extension, and if there is no php_gd2.dll,php_gd.dll, make sure that the file c:/php/extensions/php_gd2.dll does exist.

4: run the following program to test

The copy code is as follows:

Ob_end_flush ()

/ / Note that no information can be output to the browser before this, and pay attention to whether auto_prepend_file is set.

Header ("Content-type: image/png")

$im = @ imagecreate (200,100)

Or die ("cannot create image")

$background_color = imagecolorallocate ($im, 0jue 0,0)

$text_color = imagecolorallocate ($im, 230,140150)

Imagestring ($im, 3,30,50, "A Simple Text String", $text_color)

Imagepng ($im)

15: what is the UBB code

UBB code is a variant of HTML, and it is a special TAG adopted by Ultimate Bulletin Board (a foreign BBS program, which is also used in many places in China).

Even if HTML is banned, you can still use UBBCode? To make it happen. Maybe you'd rather use UBBCode? Instead of HTML, even if the forum allows the use of HTML, it is safer to use less code.

There are examples in Q3boy's UBB that you can run tests directly.

16: I want to change the password of the MySQL user

First of all, let's make it clear that in most cases, root permission in mysql is required to modify MySQL.

So the average user cannot change the password unless he or she requests an administrator.

Method one

Using phpmyadmin, which is the easiest, modify the user table of the mysql library

But don't forget to use the PASSWORD function.

Method two

Using mysqladmin, this is a special case of the previous declaration.

Mysqladmin-u root-p password mypasswd

After entering this command, you need to enter the original password of root, and then the password of root will be changed to mypasswd.

Change the root in the command to your user name, and you can change your own password.

Of course, if your mysqladmin can't connect to mysql server, or if you can't execute mysqladmin,

Then this method is ineffective.

And mysqladmin can't clear the password.

The following methods are used at the mysql prompt and must have root permission for mysql:

Method three

Mysql > INSERT INTO mysql.user (Host,User,Password)

VALUES ('%', 'jeffrey',PASSWORD (' biscuit'))

Mysql > FLUSH PRIVILEGES

To be exact, this is adding a user with the user name jeffrey and the password biscuit.

There is this example in the mysql Chinese reference Manual, so I wrote it out.

Note that you use the PASSWORD function, and then you use FLUSH PRIVILEGES.

Method 4

Same as method 3, except that the REPLACE statement is used

Mysql > REPLACE INTO mysql.user (Host,User,Password)

VALUES ('%', 'jeffrey',PASSWORD (' biscuit'))

Mysql > FLUSH PRIVILEGES

Method five

Use the SET PASSWORD statement

Mysql > SET PASSWORD FOR jeffrey@ "%" = PASSWORD ('biscuit')

You must also use the PASSWORD () function

But you don't need to use FLUSH PRIVILEGES.

Method 6

Use GRANT... IDENTIFIED BY statement

Mysql > GRANT USAGE ON *. * TO jeffrey@ "%" IDENTIFIED BY 'biscuit'

The PASSWORD () function is unnecessary here, and you don't need to use FLUSH PRIVILEGES.

Note: PASSWORD () [not] performs password encryption in the same way that Unix passwords are encrypted.

17: I want to know which website he connected to this page through.

The copy code is as follows:

/ / you must enter through a hyperconnection to get output.

Echo $_ SERVER ['HTTP_REFERER']

18: what should be paid attention to when the data is put into the database and taken out to display on the page

When entering the warehouse

$str=addslashes ($str)

$sql= "insert into `tab` (`content`) values ('$str')"

When leaving the library

$str=stripslashes ($str)

When displayed

$str=htmlspecialchars (nl2br ($str))

19: how to read the current address bar information

The copy code is as follows:

$s = "http://{$_SERVER['HTTP_HOST']}:{$_SERVER["SERVER_PORT"]}{$_SERVER['SCRIPT_NAME']}";

$se=''

Foreach ($_ GET as $key = > $value) {

$se.=$key. "=. $value." & "

}

$se=Preg_Replace ("/ (. *) & $/", "$1", $se)

$se?$se= "?". $se: "

Echo $s. "? $se"

20: I clicked the back button to see why what I had filled in before was missing.

This is because you use session.

Solution:

The copy code is as follows:

Session_cache_limiter ('private, must-revalidate')

Session_start ()

.

.

21: how to display the IP address in the picture

The copy code is as follows:

Header ("Content-type: image/png")

$img = ImageCreate (180,050)

$ip = $_ SERVER ['REMOTE_ADDR']

ImageColorTransparent ($img,$bgcolor)

$bgColor = ImageColorAllocate ($img, 0x2c, 0x6D, 0xAF); / / background color

$shadow = ImageColorAllocate ($img, 250 Jol 0); / / Shadow color

$textColor = ImageColorAllocate ($img, oxff,oxff,oxff); / / font color

ImageTTFText ($img,10,0,78,30,$shadow, "d:/windows/fonts/Tahoma.ttf", $ip); / / display the 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

The copy code is as follows:

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 () {

$ip1 = iptype1 ()

$ip2 = iptype2 ()

$ip3 = iptype3 ()

If (isset ($ip1) & & $ip1! = "none" & & $ip1! = "unknown") {

Return $ip1

}

Elseif (isset ($ip2) & & $ip2! = "none" & & $ip2! = "unknown") {

Return $ip2

}

Elseif (isset ($ip3) & & $ip3! = "none" & & $ip3! = "unknown") {

Return $ip3

}

Else {

Return "none"

}

}

Echo ip ()

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

First of all, there should be a DATETIME field in the table to record the time

The format is' 2003-7-15 161650 00'

SELECT * FROM `xltxlm` WHERE TO_DAYS (NOW ())-TO_DAYS (`date`)

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