Describes the use and analysis of PHP Development tools

For a while, I have been confused with the reference transfer in PHP. later I checked the manual and C source program and tested them repeatedly. I had a certain understanding of the mode in which the reference is passed in the memory, later, I wrote a summary to deepen my impression, so there should be no major problems-of course, this is in PHP4, and in later versions, I have been confused about the reference transfer in PHP for a period of time, later, I checked the manual and the C source program and tested them repeatedly. I had a certain understanding of the mode in which the references are passed in the memory. later I wrote a summary to help me better understand the concept, there should be no major issues-of course, this is in PHP4 and may change in later versions. At that time, when I wrote a summary, I wanted to exercise my English, so I made up an article. However, I am not good at English and I am too lazy to translate it. I just wanted to understand it myself. Today, I suddenly thought it was quite useful, so I am ugly here. please correct me. I am not busy.

The following is a reference clip: /* Filename: SetGetTest. php Comment on assignment by value and referrence Assuming $ var is a varialbe, its handle (pointer) is named as * var, And its content is named as @ var The memory area of @ var is referred by * var, if the * var is the same, Then the memory areas are the same, so * var is just like a pointer. 1. when $ var = $ var1 @ Var copied from @ var1, but in the different memory area, New * var assigned by the system, pointing to the memory area holding @ var * Var and * var1 are different 2. when $ var = & $ var1, * Var assigned by * var1, and the @ var is not assigned or copied, It is absolutely the same as @ var1, and in the same memory area Both * var and * var1 pointing to the memory area, that means they are the same. Passing by referrence 3. Function set1 (& $ s ){ $ Var = & $ s; } Set1 ($ var1) results: * Var1 passing to the function, and * s is the same as * var1, Then * var is the same as * s, the result is that * var is the same as * var1 And all the contents are the same obviusly. 4. Function set2 (& $ s ){ $ Var = $ s; } Set2 ($ var1) results: * Var1 passing to the function, and * s is the same as * var1, But when $ var = $ s executes, from 1. we can see @ var is the same as @ s, But * var is different from * s, so @ var and @ s is not in the same memory area, While @ s and @ var1 is sharing the same memory area, also * var1 and * s are the same. 5. Normal function return: Function get () {return $ var1 ;} Assuming the result is referred by a variable $ result. Then @ result is copied from @ var1 but * result is not the same as * var1 When $ var = get (); First you get a variable $ result, as I said above, @ result is the same as @ var1, but * result Is different from * var1, and next $ var = $ result executes. As I said in 1., you can find, @ var is the same as @ result and the same as @ var1, But * var is different from * result AND * var1; While $ var = & get () just means: * Var is the same as * result, so @ var and @ result are in the same memory area, But they are still different from those of $ var1, Both the memory area of @ var1 and * var1, 6. Returning by referrence Function & get () {return $ var1 ;} There are two ways to get the result $ Var = get (); and $ var = & get (); now I will tell the difference I. $ var = get (); The * result is the same as * var1 and so @ result and @ var1 are the same. And then $ var = $ result executes, * Var is not the same as * result, and also different from * var1, But their contents are the same. I. $ var = & get (); The * result is the same as * var1 and so @ result and @ var1 are the same. And then $ var = & $ result executes, This means $ var and $ result are the same, both of @ and * */ // The test is the following Function println ($ s = ""){ Print "$ s \ N "; } Class GetSetTest { Var $ var = null; Function setByRef (& $ arg ){ $ This-> var = & $ arg; } Function passByRef (& $ arg ){ $ This-> var = $ arg; } Function setByVal ($ arg ){ $ This-> var = $ arg; } Function & getByRef (){ Return $ this-> var; } Function getByVal (){ Return $ this-> var; } } $ O = new GetSetTest; Println ("============= setByRef getByRef ==================== "); Println ("----------------- Before change ----------------"); $ In = "before change "; $ O-> setByRef ($ in ); $ OutByVal = $ o-> getByRef (); $ OutByRef = & $ o-> getByRef (); Println ("\ $ in:". $ in ); Println ("\ $ outByVal:". $ outByVal ); Println ("\ $ outByRef:". $ outByRef ); Println ("\ $ this-> var:". $ o-> var ); Println ("----------------- After change -----------------"); $ In = "after change "; Println ("\ $ in:". $ in ); Println ("\ $ outByVal:". $ outByVal ); Println ("\ $ outByRef:". $ outByRef ); Println ("\ $ this-> var:". $ o-> var ); Println (); Println ("============= setByRef getByVal ================== "); Println ("----------------- Before change ----------------"); $ In = "before change "; $ O-> setByRef ($ in ); $ OutByVal = $ o-> getByVal (); $ OutByRef = & $ o-> getByVal (); Println ("\ $ in:". $ in ); Println ("\ $ outByVal:". $ outByVal ); Println ("\ $ outByRef:". $ outByRef ); Println ("\ $ this-> var:". $ o-> var ); Println ("----------------- After change -----------------"); $ In = "after change "; Println ("\ $ in:". $ in ); Println ("\ $ outByVal:". $ outByVal ); Println ("\ $ outByRef:". $ outByRef ); Println ("\ $ this-> var:". $ o-> var ); Println (); Println ("============= passByRef getByVal ================== "); Println ("----------------- Before change ----------------"); $ In = "before change "; $ O-> passByRef ($ in ); $ OutByVal = $ o-> getByVal (); $ OutByRef = & $ o-> getByVal (); Println ("\ $ in:". $ in ); Println ("\ $ outByVal:". $ outByVal ); Println ("\ $ outByRef:". $ outByRef ); Println ("\ $ this-> var:". $ o-> var ); Println ("----------------- After change -----------------"); $ In = "after change "; Println ("\ $ in:". $ in ); Println ("\ $ outByVal:". $ outByVal ); Println ("\ $ outByRef:". $ outByRef ); Println ("\ $ this-> var:". $ o-> var ); Println (); /* The following output is edited and added by me (Night Owl) without authorization, mainly for the convenience of viewing by later users. Yuexiao apologized to longnetpro Output result: ============= SetByRef getByRef ====================== ----------------- Before change ---------------- $ In: before change $ OutByVal: before change $ OutByRef: before change $ This-> var: before change ----------------- After change ----------------- $ In: after change $ OutByVal: before change $ OutByRef: after change $ This-> var: after change ============= SetByRef getByVal ====================== ----------------- Before change ---------------- $ In: before change $ OutByVal: before change $ OutByRef: before change $ This-> var: before change ----------------- After change ----------------- $ In: after change $ OutByVal: before change $ OutByRef: before change $ This-> var: after change ============= PassByRef getByVal ==================== ----------------- Before change ---------------- $ In: before change $ OutByVal: before change $ OutByRef: before change $ This-> var: before change ----------------- After change ----------------- $ In: after change $ OutByVal: before change $ OutByRef: before change $ This-> var: after change */ ?>