（六）C 语言之结构体

最新推荐文章于 2025-01-21 21:14:23 发布

原创最新推荐文章于 2025-01-21 21:14:23 发布 · 190 阅读

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8 篇文章

订阅专栏

1.1 结构体类型定义及结构体变量定义
1.1.1
略过

1.2 结构体做函数参数

1.2.1 结构体赋值编译器行为研究

typedef struct Teacher
{
	char name[32];
	int age;
} Teacher;

int main()
{
	Teacher t1 ={"zhangsan",32};
	Teacher t2 ;  
	t2 =t1;                //=号操作下 编译器的行为    
    //编译器给我们提供 简单 =号 赋值操作 。。。我们要顺从
	printf("t2.name =%s\n",t2.name);
	printf("t2.age =%d\n",t2.age);
	return 0;
}

1.2.2 结构体变量做函数参数 VS结构体指针做函数参数

typedef struct Teacher
{
	char name[32];
	int age;
} Teacher;

void copyTeacher1(Teacher to, Teacher from)
{
	to =from;
}
void copyTeacher2(Teacher *to, Teacher *from)
{
	*to = *from;
}
int main()
{
	Teacher t1 ={"zhangsan",32};
	Teacher t2 ;  
	//copyTeacher1(t2,t1);   //error
	copyTeacher2(&t2,&t1);
	printf("t2.name =%s\n",t2.name);
	printf("t2.age =%d\n",t2.age);
	return 0;
}

在这里插入图片描述

1.2.3

1.3 结构体中套一级指针

1.3.1


typedef struct Teacher
{
	char name[32];
	char * aliname;
	int age;
} Teacher;

int GetTeacher(Teacher ** pt ,int num)
{
	int i =0;
	Teacher * tmp = NULL;
	tmp = (Teacher*)malloc(sizeof(Teacher)*num);
	if(tmp == NULL) return -1;
	memset(tmp,0,sizeof(Teacher) * num );
	for(i =0;i<num ;i++)
	{
		tmp[i].aliname = (char*)malloc(30);
	}
	*pt  =tmp; //二级指针 形参 去间接的修改 实参 的值
	return 0;
}

void freeTeacher(Teacher **p ,int num)
{
	int i =0;
	Teacher * tmp =NULL;
	if(p == NULL) return ;
	tmp = *p;
	for(i =0;i<num;i++)
	{
		if(tmp[i].aliname != NULL)
			free(tmp[i].aliname);
	}
	free(tmp);
	*p = NULL;
}

1.4 结构体中套二级指针
1.4.1


typedef struct Teacher
{
	char name[32];
	char * aliname;
	char **stuname;
	int age;
} Teacher;

int GetTeacher(Teacher ** pt ,int num)
{
	int i =0,j=0;
	Teacher * tmp = NULL;
	tmp = (Teacher*)malloc(sizeof(Teacher)*num);
	if(tmp == NULL) return -1;
	memset(tmp,0,sizeof(Teacher) * num );
	for(i =0;i<num ;i++)
	{
		char ** p= NULL;
		tmp[i].aliname = (char*)malloc(30);
		p = (char**)malloc(sizeof(char*) *3);
		for( j = 0; j<3;j++)
		{
			p[j] =(char*)malloc(120);
		}
		tmp[i].stuname = p;
	}
	*pt  =tmp; //二级指针 形参 去间接的修改 实参 的值
	return 0;
}

void freeTeacher(Teacher **p ,int num)
{
	int i =0;
	Teacher * tmp =NULL;
	if(p == NULL) return ;
	tmp = *p;
	for(i =0;i<num;i++)
	{
		if(tmp[i].aliname != NULL)
			free(tmp[i].aliname);
	}
	free(tmp);
	*p = NULL;
}