Explain C language 12 in detail (C language series)

Catalog

Preface ：

The concept of structure ：

The grammatical structure of the structure ：

How to call a structure ：

The relationship between structure and object ：

Access to structure members ：

​ Edit structure parameters : 

Value transfer call ：

Address call ：

Select the reason for the address call ：

Conclusion ：

Conclusion ：

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Preface ：

Let's discuss with you this time C The structure of language , This section is just a brief introduction to the structure , For more detailed explanation, please refer to the sharing with you in the later small and medium-sized editors .

The concept of structure ：

In Xiaobian's view, a structure is a set of values , But the types of values can be different .

The grammatical structure of the structure ：

How to call a structure ：

  When an object is created in the main function, the structure is called , As shown in the figure below .

The relationship between structure and object ：

The structure type is just like the drawing in our life , When we create a structure object in the main function , We can regard it as our house , When we want to build a house, the internal structure of the house needs drawings to show us . Similarly, when we create a structural variable , We need to know the specific types of this object .（ As shown in the figure below ）

Access to structure members ：

.  Access and ->  visit

See the following code for details :

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
struct B
{
	char c;
	short s;
	double d;
};
struct stu
{
	struct B sb;
	char name[20];
	int age;
	char id[20];
};
int main()
{
	struct stu s = { {'w',20,3.14}," Zhang San ",30,"202220034" };
	// use “.” visit 
	printf("%c\n", s.sb.c);
	// use “->” visit 
	printf("%s\n", s.id);
	// When using pointer access 
	struct stu* ps = &s;
	// use “.” visit 
	printf("%c\n", (*ps).sb.c);
	// use “->” visit 
	printf("%s\n", ps->id);
	return 0;
}

The code runs as follows ：

Structural parameters : 

Value transfer call ：

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
// Value transfer call 
#include<stdio.h>
struct B
{
	char c;
	short s;
	double d;
};
struct stu
{
	struct B sb;
	char name[20];
	int age;
	char id[20];
};
void print1(struct stu t)
{
	printf("%c %d %lf %s %d %s\n", t.sb.c, t.sb.s, t.sb.d, t.name, t.age, t.id);
}
int main()
{
	struct stu s = { {'w',20,3.14}," Zhang San ",30,"202220034" };
	print1(s);// Value transfer call 
	return 0;
}

The code screenshot is as follows ：

  shortcoming ： Most of the space is wasted when calling by value .

Address call ：

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
// Address call 
#include<stdio.h>
struct B
{
	char c;
	short s;
	double d;
};
struct stu
{
	struct B sb;
	char name[20];
	int age;
	char id[20];
};
void print2(struct stu* ps)
{
	printf("%c %d %lf %s %d %s\n", ps->sb.c, ps->sb.s, ps->sb.d, ps->name, ps->age, ps->id);
}
int main()
{
	struct stu s = { {'w',20,3.14}," Zhang San ",30,"202220034" };
	print2(&s);// Address call 
	return 0;
}

The code screenshot is as follows ：

advantage ： Higher efficiency of parameter transmission , And you can change the original value .

Select the reason for the address call ：

When a function passes parameters , Parameters need to be stacked . If you pass a structure object , The structure is too large , The system overhead of parameter stack pressing will be relatively large , So it will lead to performance degradation .

Conclusion ：

When structures transmit parameters , Pass the address of the structure .

Conclusion ：

This editor mainly shares a small part of knowledge about structure with you , Pay attention to small make up , Xiaobian will take you to continue to explore the deeper knowledge behind , Remember to like it, or you won't find it next time ！ I hope that's helpful , If there are any mistakes in the article, you are also welcome to point out the maze for Xiaobian in time （ I'd like to thank you guys first ！）