The second part of the travel notes of C (Part II) structural thinking: Zen is stable; all four advocate structure

Catalog

（ one ）  Declaration of a structure

1.1 The basics of structure

1.2  Statement of structure

1.3  Type of structure member

（ Ii. ）  Structure variable definition and initialization

（ 3 ） Access to structure members  

（ boss ）  Structural parameters

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  《C travel 》 special column   《 Xiao Xuan's C Tour 》

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（ one ）  Declaration of a structure

1.1 The basics of structure

         Structure is A collection of values , These values are called member variables . Each member of a structure can be a variable of a different type .

         stay C Language in , Structure (struct) It's a data structure , yes C Aggregate data types in languages (aggregate data type) One kind of . A structure can be declared as Variable 、 The pointer or Array etc. , In order to achieve more complex data structure . The structure is also the of some elements aggregate , these Elements are called members of the structure (member), And these members can be of different types , Members usually visit by name .

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        In the actual project , Structures are abundant . R & D personnel often use structures to encapsulation Some properties to form new types . because C The internal program of the language is relatively simple , Researchers often use structures to create new products “ attribute ”, The purpose is to simplify the operation .

         The structure is in function Is not simple , Its main function is encapsulation . The advantage of encapsulation is that it can be reused . So that users don't have to care what this is , Just use it by definition .

         To make a long story short , The appearance of structure can help us better describe a complex object .

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1.2  Statement of structure

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  for example , Describe a student ：

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  1.3  Type of structure member

         The members of a structure can be scalars 、 Array 、 The pointer , Even other structures .

         Members of a structure can contain other structures , You can also include a pointer to your structure type The pointer , And usually this kind of The pointer Is used to implement some more advanced data structures, such as Linked list and Trees etc. .     

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（ Ii. ）  Structure variable definition and initialization

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（ 3 ） Access to structure members  

         Structure variable access member The members of structural variables are through    Dot operator （.）  Access to the . The dot operator accepts two operands . for example ：

We can see   s  There are members    name   and   age  ; How do we visit s Members of ？ 

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Structure pointers access members that point to variables Sometimes we don't get a structure variable , It is Pointer to a structure . How do I access members ？

as follows ：

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（ boss ）  Structural parameters

Go straight to the code , Let's judge the following   print1  and   print2  Which function is better ？

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The answer is ： The preferred print2 function . reason ：

Simply speaking ： One is Value transfer call （1）, One is Address call （2）

In this way, it can avoid repeatedly generating large structural space , Increase of efficiency

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  Conclusion ： When structures transmit parameters , To transfer the address of the structure .