《C语言程序设计》第4版 何钦铭、颜晖主编 课后习题答案 第9章 课后习题

P226页

练习9-1,9-2,9-3

#include<stdio.h>//练习9-1 
struct plural{
	double real;
	double imag;
};
int main(void)
{
	struct plural number;
	printf("实部，虚部：");
	scanf("%.2lf%.2lf",&number.real,&number.imag);
//	printf("%lf",number.imag);
//	printf("此复数为；%.2lf+%.2lfi",number.real,number.imag);
	
	return 0;
}

#include<stdio.h>//练习9-2 
struct birthday{
	int year;
	int month;
	int day;
};
struct student
{
	int num;
	char name[10];
	int math,english,computer;
	struct birthday bir;
	double average;
};
int main(void)
{
	struct student s,max;
	int n,i,j;
	
	printf("Enter n:");
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		printf("请输入学号；");
		scanf("%d",&s.num);
		printf("请输入姓名；");
		scanf("%s",s.name);
		printf("请输入数学，英语，计算机成绩：");
		scanf("%d%d%d",&s.math,&s.english,&sputer); 
		printf("请输入出生年份；");
		scanf("%d",&s.bir.year);
		printf("请输入出生月份:");
		scanf("%d",&s.bir.month);
		printf("请输入出生日期：");
		scanf("%d",&s.bir.day); 
		s.average=(sputer+s.english+s.math)/3.0;
		if(i==1)//第一个平均分 
		{
			max=s;//第一个默认最大值 
		} else if(s.average>max.average)//成员比较 
		{
			max=s;//整体赋值 
		}
	} 
	printf("学号\t姓名\t数学\t英语\t计算机\t平均分\t年—月—日\n");
	printf("%d\t%s\t%d\t%d\t%d\t%.2lf\t%2d-%2d-%2d\n",max.num,max.name,max.math,max.english,maxputer,max.average,max.bir.year,max.bir.month,max.bir.day);
	
	return 0;
}

#include<stdio.h>//练习9-3 
#define N 50
struct student
{
	int num;
	char name[10];
	int math,english,computer;
	double average;
};
int main(void)
{
	struct student s[N];
	int n,i,j;
	
	printf("Enter n:");
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		printf("请输入学号；");
		scanf("%d",&s[i].num);
		printf("请输入姓名；");
		scanf("%s",s[i].name);
		printf("请输入数学，英语，计算机成绩：");
		scanf("%d%d%d",&s[i].math,&s[i].english,&s[i]puter);
		s[i].average=(s[i]puter+s[i].english+s[i].math)/3.0;
	} 
	printf("学号\t姓名\t数学\t英语\t计算机\t平均分\n");
	for(i=0;i<n;i++)
	{
		printf("%d\t%s\t%d\t%d\t%d\t%.2lf\n",s[i].num,s[i].name,s[i].math,s[i].english,s[i]puter,s[i].average);
	}
	
	return 0;
}

P228页

练习9-4,9-5

#include<stdio.h>//练习9-4 
struct student{
	int num;
	char name[10];
	int math,english,computer;
};
int main(void)
{
	struct student stu[5]={{101,"zhang",86,98,88},{103,"li",65,67,68},{106,"wang",55,54,58},{102,"qian",65,62,64},{109,"sun",86,49,58}};
	int i; 
	
	printf("学号\t姓名\t数学\t英语\t计算机\n");
	for(i=0;i<5;i++)
	{
		printf("%d\t%s\t%d\t%d\t%d\n",stu[i].num,stu[i].name,stu[i].math,stu[i].english,stu[i]puter);
	}
	
	return 0;
}

#include<stdio.h>//练习9-5 
struct student
{
	int num;
	char name[10];
	int math,english,computer;
	double average;
};
int main(void)
{
	struct student s[10];
	int i,max=0,min=0;
	
	for(i=0;i<10;i++)
	{
		printf("请输入学号；");
		scanf("%d",&s[i].num);
		printf("请输入姓名；");
		scanf("%s",s[i].name);
		printf("请输入数学，英语，计算机成绩：");
		scanf("%d%d%d",&s[i].math,&s[i].english,&s[i]puter);
		s[i].average=(s[i]puter+s[i].english+s[i].math)/3.0;
		if(s[i].average>s[max].average){
			max=i;
		} else if(s[i].average<s[min].average){
			min=i;
		}
	} 
	printf("平均分最高和最低的学生信息为；\n");
	printf("学号\t姓名\t数学\t英语\t计算机\t平均分\n");
	printf("%d\t%s\t%d\t%d\t%d\t%.2lf\n",s[max].num,s[max].name,s[max].math,s[max].english,s[max]puter,s[max].average);
	printf("%d\t%s\t%d\t%d\t%d\t%.2lf\n",s[min].num,s[min].name,s[min].math,s[min].english,s[min]puter,s[min].average);
	
	return 0;
}

P232页

练习9-6,9-7

#include<stdio.h>//练习9-6 
struct student
{
	int num;
	char name[10];
	int math,english,computer;
	double average;
};
int main(void)
{
	struct student stu,*p;
	p=&stu;
	printf("请输入学号；");
	scanf("%d",&(*p).num);
	printf("请输入姓名；");
	scanf("%s",(*p).name);
	printf("请输入数学，英语，计算机成绩：");
	scanf("%d%d%d",&(*p).math,&(*p).english,&(*p)puter);
	(*p).average=((*p)puter+(*p).english+(*p).math)/3.0;
	printf("学号\t姓名\t数学\t英语\t计算机\t平均分\n");
	printf("%d\t%s\t%d\t%d\t%d\t%.2lf\n",p->num,p->name,p->math,p->english,p->computer,p->average);

	return 0;
}

#include<stdio.h>//练习9-7 
#define N 50
struct student
{
	int num;
	char name[10];
	int math,english,computer;
	double average;
};
void alter(struct student s[],int n,int num,int math)
{
	int i,k;
	char ch;
	for(i=0;i<n;i++)
	{
		if(num==s[i].num){
			break;
		}
	}
	if(i<n){
	    printf("%d\t%s\t%d\t%d\t%d\t%.2lf\n",s[i].num,s[i].name,math,s[i].english,s[i]puter,(s[i]puter+s[i].english+math)/3.0);
	    printf("请再次确认：y or n\n"); 
	    ch=getchar();
		if(ch=='y'){
		    s[i].math=math;
		    s[i].average=(s[i]puter+s[i].english+s[i].math)/3.0;
		    puts("修改成功");
		    for(i=0;i<n;i++)
		    {
		        printf("%d\t%s\t%d\t%d\t%d\t%.2lf\n",s[i].num,s[i].name,s[i].math,s[i].english,s[i]puter,s[i].average);
	        }
	    } 
    }
	else printf("没有找到");
}
int main(void)
{
	struct student s[N],x;
	int n,i,j,k,num,math;
	
	printf("Enter n(n<50):");
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		printf("请输入学号；");
		scanf("%d",&s[i].num);
		printf("请输入姓名；");
		scanf("%s",s[i].name);
		printf("请输入数学，英语，计算机成绩：");
		scanf("%d%d%d",&s[i].math,&s[i].english,&s[i]puter);
		s[i].average=(s[i]puter+s[i].english+s[i].math)/3.0;
	} 
	printf("请输入待修改学生的学号：");
	scanf("%d",&num);
	printf("请输入待修改数学成绩；");
	scanf("%d",&math);
	getchar();//接受输入数学成绩后面的那个回车，避免影响确认信息 
	alter(s,n,num,math);//只可以将要修改的成员传过去，不可以将一整个结构体变量传过去 

	return 0;
}