#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
1、结构体类型定义
2、结构体变量定义
3、结构体变量的初始化
4、typedef改类型名
5、点运算符和指针法操作结构体
6、结构体也是一种数据类型，复合类型，自定义类型
*/

//1、结构体类型定义
//struct关键字
//struct Teacher合一起才是类型
//{}后面有分号
struct Teacher
{
    
	char name[50];
	int age;
};

//2、结构体变量定义
//1.先定义类型，再定义变量（常用）
struct Teacher t1; //全局变量


//2. 定义类型同时定义变量
struct Teacher2
{
    
	char name[50];
	int age;
}t3 = {
    "tom", 66};

struct
{
    
	char name[50];
	int age;
}t5;

//3、结构体变量的初始化
//定义变量时直接初始化，通过{}
struct Teacher t7 = {
     "lily", 18 };

//4、typedef改类型名
typedef struct Teacher3
{
    
	char name[50];
	int age;
}Teacher3;

struct Teacher3 t8;
Teacher3 t9;

int main(void)
{
    
	//1.先定义类型，再定义变量（常用）
	struct Teacher t2; //局部变量

	printf("%s, %d\n", t7.name, t7.age);

	//5、点运算符和指针法操作结构体

	/*
	struct Teacher
	{
		char name[50];
		int age;
	};
	*/
	strcpy(t2.name, "xiaoming");
	t2.age = 22;
	printf("%s, %d\n", t2.name, t2.age);

	//结构体指针变量，没有指向空间，不能给其成员赋值
	struct Teacher *p = NULL;
	p = &t2;
	strcpy(p->name, "xiaojiang");
	p->age = 22;
	printf("%s, %d\n", p->name, p->age);

	return 0;
}

可以在栈上分配内存，可以在堆上分配内存

#define  _CRT_SECURE_NO_WARNINGS 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

typedef struct Teacher
{
    
	char name[64];
	int age ;
	int id;
}Teacher;

void printTeacher(Teacher *array, int num)
{
    
	int i = 0;
	if(array == NULL)
		return ;
	
	for (i=0; i<num; i++)
	{
    
		printf("age:%d \n", array[i].age);
	}
}

void sortTeacer(Teacher *array, int num)
{
    
	int		i,j;
	Teacher tmp;

	for (i=0; i<num; i++)
	{
    
		for (j=i+1; j<num; j++)
		{
    
			if (array[i].age > array[j].age)
			{
    
				tmp = array[i];  
				array[i] = array[j];
				array[j] = tmp;
			}
		}
	}
}

#if 0

// 结构体数组 输入老师的年龄，排序
int main(int argc, const char * argv[])
{
    
	int			i = 0;
	Teacher		Array[3];  //在stack 分配内存
	int			num = 3;

	for (i=0; i<num; i++)
	{
    
		printf("\nplease enter age:");
		scanf("%d", &(Array[i].age) );
	}

	printTeacher(Array, num);

	sortTeacer(Array, num);

	printf("排序之后\n");

	printTeacher(Array, num);

	return 0;
}

#else

Teacher * createTeacher(int num)
{
    
	Teacher * tmp = NULL;
	tmp = (Teacher *)malloc(sizeof(Teacher) * num); //	Teacher		Array[3]
	if (tmp == NULL)
	{
    
		return NULL;
	}
	return tmp; 

}

void FreeTeacher(Teacher *p)
{
    
	if (p != NULL)
	{
    
		free(p);
		p = NULL;
	}

	return ;
}

int main(int argc, const char * argv[]) 
{
    
	int			i = 0;
	int			num = 3;
	Teacher *pArray = NULL;
	pArray = createTeacher(num);

	for (i=0; i<num; i++)
	{
    
		printf("\nplease enter age:");
		scanf("%d", & (pArray[i].age) );
	}

	printTeacher(pArray, num);

	sortTeacer(pArray, num);

	printf("排序之后\n");

	printTeacher(pArray, num);

	FreeTeacher(pArray);

	return 0;
}

#endif

测试结果