Php prompts several solutions for undefined index

When $ _ post [''] and $ _ get [''] are used to obtain parameters in the formNotice: Undefined index :--------;

We often receive Undefined index errors when receiving data from form POST, as follows: $ act =$ _ POST ['action'];
The above code always prompts
Notice: Undefined index: act in D: \ test \ post. php on line 20
In addition
Notice: Undefined variable: Submit... and so on

The above are PHP prompts rather than errors. PHP itself can be directly used without declaring the variables in advance, but a prompt will be prompted if the variables are not declared. Generally, when a website is a formal website, it will turn off the prompts and even the error message.

Solution:

Method 1: Modify server configurations
Modify the error display mode in the error configuration in php. ini: Change error_reporting = E_ALL

Error_reporting = E_ALL &~ E_NOTICE

After modification, restart the APCHE server.

Method 2: Initialize the variable.

Method 3: Judge isset ($ _ post ['']), empty ($ _ post ['']) if -- else

Method 4: Add @ before the notice code appears. @ indicates that the line has an error or the warning is not output. @ $ username = $ _ post ['username'];
Add a @ in front of the variable, such as if (@ $ _ GET ['action'] = 'save '){...

Method 5: The last one is very practical. It is a function written by someone else, through which values are transmitted.

Define a function:
Copy codeThe Code is as follows:
Function _ get ($ str ){
$ Val =! Empty ($ _ GET [$ str])? $ _ GET [$ str]: null;
Return $ val;
}


Then, replace $ _ get ['str'] With _ GET ('str ~

[PHP-Core-Error]

Error_reporting = E_ALL &~ E_NOTICE
The error report level is the superposition of bit fields. We recommend that you use E_ALL | E_STRICT
; 1 E_ERROR fatal runtime error
; 2 E_WARNING runtime warning (non-fatal error)
4. parsing error during E_PARSE Compilation
; 8 E_NOTICE runtime reminder (often a bug or intentionally)
; 16 E_CORE_ERROR fatal error during PHP startup
32 _ core_warning warning during initialization (non-fatal error) during PHP startup)
; 64 E_COMPILE_ERROR fatal error during compilation
; 128 E_COMPILE_WARNING warning during compilation (non-fatal error)
256 User-Defined fatal error
; 512 user_warning User-Defined warning (non-fatal error)
1024 E_USER_NOTICE User-Defined notifications (often bugs, or intentionally)
; 2048 E_STRICT code standardization warning (how to modify to forward compatibility)
; 4096 E_RECOVERABLE_ERROR is close to a fatal runtime error. If it is not captured, it is treated as E_ERROR.
; 6143 all except E_STRICT errors (8191 in PHP6, that is, all errors)