作业 3 利用分支与循环结构解决问题

2

#include<stdio.h>
int main(void)
{
 
 int count,i,n;
 double grade,total;
 printf("Enter n:");
 scanf("%d",&n);
 total=0;
 count=0;
 for(i=1;i<=n;i++){
  
  printf("Enter grade#%d:",i);
  scanf("%lf",&grade);
  total=total+grade;
  if(grade>=60){
   
   count++;
  }
 }
 printf("Grade average=%.2f\n",total/n);
 printf("Number of success=%d\n",count);
 return 0;
}

3.

#include<stdio.h>
int main(void)
{
 int letter,digit,blank,other;
 char ch;
 int i;
 letter=digit=blank=other=0;
 printf("Enter 15 characters:");
 for(i=1;i<=15;i++){
  ch=getwchar();
  if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
  letter++;
  else if(ch>='0'&&ch<='9')
  digit++;
  else if((ch='\n')||(ch=' '))
  blank++;
  else
  other++;
 
 }
 printf("letter=%d,digit=%d,blank=%d,other=%d\n",letter,digit,blank,other);
 return 0;
}

 

4..

#include<stdio.h>
int main(void)
{
 int year;
 printf("Enter The year:");
 scanf("%d",&year);
 while(year!=-1){
  if((year%4==0&&year%100!=0)||(year%400==0)){
   printf("The year is 闰年\n");
   printf("Enter The year:");
   scanf("%d",&year);
  }
  else{
   printf("The year is not 闰年\n");
   printf("Enter The year:");
   scanf("%d",&year);
  }
 }
 return 0;
}

5.

#include<stdio.h>
int main(void)
{
 char ch;
 printf("Enter the level(A B C D E):");
 ch=getchar();
 switch(ch){
 case'A':printf("The level is 90~100\n");break;
 case'B':printf("The level is 80~89\n");break;
 case'C':printf("The level is 70~79\n");break;
 case'D':printf("The level is 60~69\n");break;
 case'E':printf("The level is 0~59\n");break;
 }
 return 0;
}
  

6.

#include<stdio.h>
int main(void)
{
 int choice,i;
 double price;
 for(i=1;i<=5;i++){
  printf("[1]Select apples\n");
  printf("[2]Select pears\n");
  printf("[3]Select oranges\n");
  printf("[4]Select grapes\n");
  printf("[0]Select exit\n");
  printf("Enter choice:");
  scanf("%d",&choice);
  if(choice==0)
   break;
  switch(choice){
  case 1:price=3.00;break;
  case 2:price=2.50;break;
  case 3:price=4.10;break;
  case 4:price=10.20;break;
  default:price=0.00;break;
  }
  printf("price=%0.2f\n",price);
 }
 return 0;
}