Php summary 6.0 -- custom function, reference value passing, php6.0

Php summary 6.0 -- custom function, reference value passing, php6.0

6.1 User-Defined Functions

Function Name (parameter [= default value], parameter [= default value]...) {

Function body

[Return val];

}

1) No parameter is returned

2) if a parameter exists, no response is returned.

3) if any parameter is returned

The code in the function is not executed immediately and will be executed only when called.

Call: function name ([parameter list])

Question: What are the differences between the following two functions?

Function demo {

Echo 1111;

} // 1111 is printed on the page and cannot be assigned to a variable.

 

Function demo {

Return 1111;

} // It is not printed on the page, but can be assigned to a variable.

4) recursive functions

Recursive functions must be terminated.

It is often used in php to recursively Delete directory files.

6.2 reference and pass value of a Variable

Reference Value: php allows multiple variables to point to the same memory space.

The reference transmits the content.

Question: What are the output of the following two programs?

<? Php $ a = 3; $ B = $ a; $ a = 4; echo $ B; // 3?> <? Php $ a = 3; $ B = & $ a; $ a = 4; echo $ B; // 4?>