c++ 基础知识-结构体

c++ 基础知识-结构体

1.初始化结构体，结构体数组

#include <iostream>  
#include <string>  
using namespace std;
struct Student
{
	string name;
	int age;
};
int main()
{
	Student stuArr[] = {{"a",1},{"b",2},{"c",3}};
	stuArr[1].name = "d";
	stuArr[1].age = 4;
	for (int i = 0;i<sizeof(stuArr)/sizeof(stuArr[0]);i++)
	{
		cout<<"name :"<<stuArr[i].name
			   <<" "
			   <<"age :"<<stuArr[i].age<<endl;
	}
	return 0;
} 

2.结构体指针

#include <iostream>  
#include <string>  
using namespace std;

struct Student
{
	string name;
	int age;
};
int main()
{
	Student stu;
	stu.name = "a";
	stu.age = 2;
	Student *p = &stu;
	//*p->name = "b";
	//*p->age = 5；
	cout<<"name :"<<p->name<<endl;//注意是p->name 不是*p->name
	cout<<"age :"<<p->age<<endl;
	return 0;
} 

3.结构体嵌套

#include <iostream>  
#include <string>  
using namespace std;

struct Learn
{
	int math;
	int english;
};
struct Student
{
	string name;
	int age;
	struct Learn learn;
};

int main()
{
	Student stu;
	stu.name = "a";
	stu.age = 5;
	//Learn learn;
	stu.learn.english = 10;
	stu.learn.math = 20;
	cout<<stu.learn.english<<endl;
	cout<<stu.learn.math<<endl;
	return 0;
} 

4.结构体作为函数参数

#include <iostream>  
#include <string>  
using namespace std;

struct Student
{
	string name;
	int age;
};

//void CoutStruct(Student stu);//值传递，需要重新开辟空间，浪费内存
void CoutStruct(Student * stu);//指针，节省空间
//void CoutStruct(const Student * stu);//通常加const,保证输入不改变
int main()
{
	Student stu;
	stu.age = 19;
	stu.name = "a";
	Student * p = &stu;
	CoutStruct(p);
	cout<<"age: "<<stu.age<<endl;//值传递，指针（地址）传递输出结果不同，指针操作的是地址，数据改变，值传递数据不改变
	return 0;
} 

//void CoutStruct(Student stu)
//{
//	stu.age = 30;
//	cout<<"age: "<<stu.age<<endl;
//	cout<<"name: "<<stu.name<<endl;
//}

void CoutStruct(Student * stu)
{
	stu->age = 30;
	cout<<"age: "<<stu->age<<endl;
	cout<<"name: "<<stu->name<<endl;
}