Functions of the @ symbol in php and the role of the & symbol before the php function

What is the role of the @ symbol in php and the role of the & amp; symbol before the php function? Used to hide errors. 2. When will it be used? Some errors will abort the program, but in fact it may be just a local error. it is definitely not good because of a small error, therefore, adding a "@" in front of a possible error in your expectation can prevent the @ symbol in php and the & symbol before the php function from being caused by an error.

. Role? Used to hide incorrect
2. when should I use it? Some errors will abort the program, but in fact it may be just a local error. it is definitely not good because of a small error, therefore, you can add "@" in front of a possible error in your expectation to Prevent program suspension caused by errors. For example, "$ con = @ mysql_connect ($ MYhost, $ DB_name, $ DB_PassWord );"
3. what should I pay attention?
@ Is just a method to hide your ears and ears. it only hides errors, but does not solve them.

?

?

Answer to the second question:

?

?

The role of the & symbol before the php function:
Take a look at the following code. there is a & symbol before the function test.
Function & test (){
// Declare a static variable
Static $ B = 0;
$ B = $ B + 1;
Echo $ B;
Return $ B;
}
The call method and output result are as follows:
$ A = test (); // This statement outputs the value of $ B as 1.
$ A = 5;
$ A = test (); // This statement outputs the value of $ B to 2.
$ A = & test (); // This statement outputs the value of $ B to 3.
$ A = 5;
$ A = test (); // This statement outputs a value of 6 for $ B.
Note:
In this way, $ a = test (); does not actually return a function reference, which is no different from a common function call.
As for the reason: this is a PHP rule
PHP requires that $ a = & test (); is used to obtain the function reference and return.
As for what is reference return (in the php Manual, reference return is used when you want to use a function to find the variable on which the reference should be bound .)
This sentence in the manual may not be easy to understand. Read the following explanation:
$ A = test () is used to call a function. it only assigns the value of the function to $ a. any change made to $ a does not affect $ B in the function.
In the $ a = & test () method, the function calls the memory address of the $ B variable in return $ B and the memory address of the $ a variable,
Point to the same place.
This is equivalent to the effect ($ a = & B;). Therefore, the value of $ a is changed and the value of $ B is changed. Therefore, the following code is executed:
$ A = & test ();
$ A = 5;
Later, the value of $ B is changed to 5.