Php function extraction

[Switch] php function reference is reprinted from? Is hosserer finally edited? Hosserer? An image metaphor: Reference: You are my shadow, what I wear, what I wear, and what I wear. you are unset, and I am still me. Pass value: You are a photo of me at a certain time, or you are an independent thing. I said you are an apple, and you are an apple. it has nothing to do with me. Reprinted as follows :? The & amp; symbol added before the php function indicates [conversion] php function reference.

Reprinted from? Hosserer

Final editing? Hosserer

? An image metaphor: Reference: You are my shadow, my clothes, and your clothes. you are unset, and I am still me. Pass value: You are a photo of me at a certain time, or you are an independent thing. I said you are an apple, and you are an apple. it has nothing to do with me. Reprinted as follows: ? The "&" symbol added before the php function indicates that the function is referenced and returned. what is the role of adding & symbol before the php function? Php code? Function & test () { Static $ B = 0; // declare a static variable $ B = $ B + 1; Echo $ B; Return $ B; } $ 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 (); // The value of $ B is 6? The following explains: 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 .) The example above is as follows: $ 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 ...... What is the meaning of adding the & symbol before the php variable? First look at an example Php code? $ Foo = 321 ;??? $ Bar = & $ foo ;???? $ Bar = 123 ;??? Print $ foo; $ Foo = 321; $ Bar = & $ foo ;? $ Bar = 123; Print $ foo; what is the output result? Php code? 123 ???? Why? Changing new variables will affect the original variables. this assignment operation is faster. Note: Only named variables can assign values to addresses. That is to say, if the value of $ bar is changed, the value of $ foo is changed.