c语言共用体实现设计个人名片,包含姓名,职业,电话

//共用体实例 你看看行不
#include <stdio.h>
#include <windows.h>
#include <string.h>

//共用体
union businessCard
{
	char name[20];  //存储姓名
	char job[20];  //存储职业
	char phoneNum[13];  //存储电话号码
};

void main(void)
{
	businessCard card;
	FILE *fp;
	if(!(fp=fopen("businessCard.txt","a+")))
	{
		printf("文件打开失败\n");
		exit(0);
	}
	else
	{
		printf(">输入姓名：");
		scanf("%s",card.name);
		fprintf(fp,"%s\n",card.name);
		printf(">输入职业：");
		scanf("%s",card.job);
		fprintf(fp,"%s\n",card.job);
		printf(">输入电话：");
		scanf("%s",card.phoneNum);
		fprintf(fp,"%s\n",card.phoneNum);
	}
	fclose(fp);

	//从已存储文件中读取名片
	if(!(fp=fopen("businessCard.txt","r")))
	{
		printf("文件打开失败……\n");
		exit(0);
	}
	int i,j;
	i=1,j=1;
	char buf[20]="";
	while(!feof(fp))
	{
		if(i==1 || i-j*3==1)
		{
			fgets(card.name,20,fp);
			if(strcmp(card.name,buf)!=0)
			printf(">姓名：%s",card.name);
		}

		if(i==2 || i-j*3==2)
		{
			fgets(card.job,20,fp);
			printf(">职业：%s",card.job);
		}
	
		if(i==3 || i-j*3==3)
		{
			fgets(card.phoneNum,20,fp);
			printf(">电话：%s\n",card.phoneNum);
			strcpy(buf,card.phoneNum);
			j++;
		}
		i++;
	}
	fclose(fp);
}