Explanation of php error shielding error_reporting

In Windows: The program that was originally running normally in php tutorial 4.3.0, why did multiple errors be reported in 4.3.1? The General prompt is: Notice: Undefined varialbe: variable name.
For example, the following code is available:
Copy the Code as follows:
If (! $ Tmp_ I ){
$ Tmp_ I = 10;
}

Run normally in 4.3.0. When running 4.3.1, the system prompts Notice: Undefined varialbe: tmp_ I.
Question:
1. Where is the problem?
2. How should I modify this code?
3. without changing the code segment, how can I modify the settings in php. ini to make the original program in 4.3.0 run normally in the 4.3.1 environment? This error message is not displayed.

Solution:

Add one sentence at the beginning of the program:
Error_reporting (E_ALL &~ E_NOTICE); or error_reporting (E_ALL ^ E_NOTICE );

Or
Modify php. ini
Error_reporting = E_ALL &~ E_NOTICE

Related error_reporting () functions:

Error_reporting () sets the PHP error level and returns the current level.

; Error reports are reported by bit. Or add the numbers to get the expected error report level.
; E_ALL-all errors and warnings
; E_ERROR-fatal runtime error
; E_WARNING-runtime warning (non-fatal error)
; E_PARSE-parsing error during compilation
; E_NOTICE-runtime reminder (these are often caused by bugs in your code,

It may also be caused by intentional behaviors. (For example, an uninitialized variable is automatically initialized to
; Use an uninitialized variable instead of an empty string)

; E_CORE_ERROR-fatal error during PHP startup Initialization
; E_CORE_WARNING-warning occurred during PHP startup initialization (non-fatal error)
; E_COMPILE_ERROR-fatal error during compilation
; E_COMPILE_WARNING-warning during compilation (non-fatal error)
; E_USER_ERROR-error message generated by the user
; E_USER_WARNING-user-generated warning message
; E_USER_NOTICE-user-generated reminder message

Usage:

Error_reporting (0); // Disable Error Reporting
Error_reporting (E_ALL ^ E_NOTICE); // display all error messages except E_NOTICE
Error_reporting (E_ALL ^ E_WARNING ^ E_NOTICE); // display all error messages except E_WARNING E_NOTICE
Error_reporting (E_ERROR | E_WARNING | E_PARSE); // displays a runtime error, which is the same as error_reporting (E_ALL ^ E_NOTICE. Error_reporting (E_ALL); // display all errors

A php Error was encountered
Severity: Notice

Message: Undefined variable: user

Generally, if an undefined declared variable is output in the default PHP file, no error is reported, but an error is reported in the codeigniter framework, this is inconvenient for "lazy people" who want to integrate and add and modify pages. As a beginner, how can he block this error message in the code. I even used @, but many people have said that @ will greatly reduce the performance ....

Finally, I suddenly thought, was codeigniter intentionally prompted this error message? How should we block this type of error and accidentally found "How To Make codeigniter not display the Notice information ?", It turned out to be error_reporting (E_ALL) in index. php. You just need to change it
Error_reporting (E_ALL ^ E_NOTICE );
This error can be blocked without affecting other errors.

Below are some information you have found:

Error_reporting () sets the PHP error level and returns the current level.

Syntax
Error_reporting (report_level)
If the level parameter is not specified, the current error level is returned. The following items are possible values of level:

1 E_ERROR
2 E_WARNING
4 E_PARSE
8 E_NOTICE
16 E_CORE_ERROR
32 E_CORE_WARNING
64 E_COMPILE_ERROR
128 E_COMPILE_WARNING
256 E_USER_ERROR
512 E_USER_WARNING
1024 E_USER_NOTICE
2047 E_ALL
2048 E_STRICT
E_NOTICE indicates that the file is generally not recorded and used only when the program has an error, for example, an attempt to access a variable that does not exist or call stat () to view a file that does not exist.

E_WARNING is usually displayed, but the program execution will not be interrupted. This is effective for debugging. For example, call ereg () in a problematic General notation ().

E_ERROR is usually displayed and the program execution is interrupted. This mask cannot be used to trace memory configurations or other errors.

E_PARSE parses errors from the syntax.
E_CORE_ERROR is similar to E_ERROR, but does not include errors caused by the PHP core.
E_CORE_WARNING is similar to E_WARNING, but does not include PHP core error warnings.

PHP Error Report
The php. ini file contains many configuration settings. You should have set up your php. ini file and put it in the appropriate directory, as shown in instructions for installing PHP and Apache 2 on Linux. When debugging a PHP application, you should know two configuration variables. The two variables and their default values are as follows:
Display_errors = Off
Error_reporting = E_ALL
By searching for these variables in the php. ini file, you can find the current default values of these two variables. The purpose of the display_errors variable is obvious-It tells PHP whether an error is displayed. The default value is Off. However, to make the development process easier, set this value to On:
Display_errors = On
The default value of error_reporting variable is E_ALL. This setting displays all information from poor coding practices to harmless prompts to errors. E_ALL is a little too detailed for the development process, because it displays a prompt on the screen for some trivial matters (for example, the variable is not initialized), it will mess up the browser output. I only want to see errors and bad code practices, but do not want to see harmless prompts. Therefore, replace the default value of error_reporting with the following values:
Error_reporting = E_ALL &~ E_NOTICE

Restart Apache and set all the settings. Next, we will learn how to do the same thing on Apache.

Server Error Report
Depending on what Apache is doing, opening an error report in PHP may not work, because there may be multiple PHP versions on the computer. Sometimes it is difficult to tell which PHP version Apache is using, because Apache can only view one php. ini file. I don't know which php. ini file Apache is using to configure itself as a security issue. However, there is a way to configure the PHP variable in Apache to ensure that the correct error level is set.

In addition, it is better to know how to set these configuration variables on the server side to reject or preemptible the php. ini file to provide higher-level security.
When configuring Apache, you must have been exposed to the basic configuration in the http. conf file in/conf/httpd. conf.

To add the following lines to httpd. conf to overwrite any php. ini file:
Php_flag display_errors on
Php_value error_reporting 2039
This overwrites the flag set for display_errors and the value of error_reporting in the php. ini file. The value 2039 represents E_ALL &~ E_NOTICE. If you want to use E_ALL, set the value to 2047. Similarly, restart Apache.
Next, test the Error Report on the server.

The error_reporting () function can shield some error messages, but the errors caused by the PHP core cannot be blocked, errors Caused by PHP core will directly cause PHP file compilation failure, because the writing format is not written in accordance with the PHP encoding rules, which cannot be blocked.
Copy the Code as follows:
* For now, avoid warnings of E_STRICT mode
* (This must be done before function definitions)
*/
If (defined ('e _ STRICT ')){
$ Old_error_reporting = error_reporting (0 );
If ($ old_error_reporting & E_STRICT ){
Error_reporting ($ old_error_reporting ^ E_STRICT );
} Else {
Error_reporting ($ old_error_reporting );
}
Unset ($ old_error_reporting );

The following are common examples:
Copy the Code as follows:
// Turn off all error reporting; disable all errors
Error_reporting (0 );

// Report simple running errors; Report a simple running error
Error_reporting (E_ERROR | E_WARNING | E_PARSE );

// Reporting E_NOTICE can be good too (to report uninitialized
// Variables or catch variable name misspellings ...); Including reporting uninitialized variables or spelling errors for capturing variable names
Error_reporting (E_ERROR | E_WARNING | E_PARSE | E_NOTICE );

// Report all errors before t E_NOTICE
// This is the default value set in php. ini; reports all errors but does not include E_NOTICE. This is also the default setting of php. ini.
Error_reporting (E_ALL ^ E_NOTICE );

// Report all PHP errors (bitwise 63 may be used in PHP 3); Report all errors
Error_reporting (E_ALL );

// Same as error_reporting (E_ALL); Same as above
Ini_set ('error _ report', E_ALL );