结构体初始化三种方法

小灰灰 2022-03-01 05:14 280阅读 0赞

**方法(一)：定义时赋值**

# include <stdio.h>
    struct AGE
    {
        int year;
        int month;
        int day;
    };
    struct STUDENT
    {
        char name[20];
        int num;
        struct AGE birthday;
        float score;
    };
    int main(void)
    {
        struct STUDENT student1 = {"小明", 1207041, {1989, 3, 29}, 100};
        return 0;
    }

**方法（二）：定义后赋值**

# include <stdio.h>
    # include <string.h>
    struct AGE
    {
        int year;
        int month;
        int day;
    };
    struct STUDENT
    {
        char name[20];  //姓名
        int num;  //学号
        struct AGE birthday;  /*用struct AGE结构体类型定义结构体变量birthday, 即生日*/
        float score;  //分数
    };
    int main(void)
    {
        struct STUDENT student1;  /*用struct STUDENT结构体类型定义结构体变量student1*/
        strcpy(student1.name, "小明");  //不能写成&student1
        student1.num = 1207041;
        student1.birthday.year = 1989;
        student1.birthday.month = 3;
        student1.birthday.day = 29;
        student1.score = 100;
        printf("name : %s\n", student1.name);  //不能写成&student1
        printf("num : %d\n", student1.num);
        printf("birthday : %d-%d-%d\n", student1.birthday.year, student1.birthday.month, student1.birthday.day);
        printf("score : %.1f\n", student1.score);
        return 0;
    }

**方法（三）：构造函数初始化**

利用 memset(d,0,sizeof(d))初始化

struct bign{
    	int d[1000];//位数 
    	int len;//实际位数长度 
    	bign(){
    	     memset(d,0,sizeof(d));//数组d 长度d赋值为0
    	     len=0;		
    	}
    };

**方法（四）：利用构造函数赋值**

#include <stdio.h>
    int main(){
    	struct Test{
    		int num=1;
    		int count=2;
    	
    		Test(int _num,int _count):num(_num),count(_count){ //构造函数变量不能与成员变量名相同 
    			
    	    }
    	}test(1,2); //1，2就是传入的参数。
        //Test test=Test(1,2); 依然成立
    	printf("%d",test.count);   //2 
    	return 0;
    }

**练习：初始化平面点的坐标**

#include <stdio.h>
    struct Point{
    	int x;
    	int y;
    	Point(){   //用于定义p[10]，去除则会报错
    	}
    	Point(int _x,int _y):x(_x),y(_y){
    		
    	}
    }p[10];
    int main(){
    	int num=0;
    	for(int i=1;i<=3;i++){
    		for(int j=1;j<=3;j++){
    			p[num++]=Point(i,j);
    		}
    	}
    	for(int i=0;i<num;i++){
    		printf("%d,%d\n",p[i].x,p[i].y);
    	}
    	return 0;
    }

答案：  
1,1  
1,2  
1,3  
2,1  
2,2  
2,3  
3,1  
3,2  
3,3