"C language programming", 4th Edition, edited by he Qinming and Yan Hui, after class exercise answers Chapter 3 branch structure

The first 3 Chapter after class practice answers

P057

#include<stdio.h>
int main(void)
{
	/* Statistical characters ( practice 3-4)*/{
	int n,i,letter=0,digit=0,count=0,other=0; 
	char ch;
	printf("Enter n:");
	scanf("%d",&n);
	getchar();
	printf(" Input %d Characters ：",n);
	for(i=1;i<=n;i++)
	{
		ch=getchar();
		if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
		letter++;
		else if(ch>='0'&&ch<='9')
		     digit++;
		     else if(ch==' '||ch=='\n')
		          count++;
		          else other++;
	}
	printf("letter=%d,digit=%d,count( Space or car )=%d,other=%d\n",letter,digit,count,other);}
	
	printf("\n");
	
	/* Output leap year ( practice 3-5)*/{
	int m=2000,n,y;
	printf("Enter n(21 One year in the century )：");
	scanf("%d",&n);
	printf("21 By the middle of the century %d There are leap years before ：",n);
	for(y=m;y<=n;y++)
	{
		if((y%4==0&&y%100!=0)||(y%400==0))
		printf("%d\t",y);
		else ;
	} 
    }
	
	return 0;
}

P064

#include<stdio.h>
int main(void)
{
	/* Achievement transformation （ practice 3-7）*/
	int score;
	printf("Enter score(1~100):");
	scanf("%d",&score);
	printf(" Enter the percentile score %d The corresponding five point score is ：",score); 
	if(score>=90)
	putchar('A');
	else if(80<=score)
	     putchar('B');
	     else if(70<=score)
	          putchar('C');
	          else if(60<=score)
	               putchar('D');
	               else putchar('E');
	               
	printf("\n\n");
	
	/* Check the unit price of fruit ( practice 3-8）*/
	int i,choice;
	double price;
	
	printf("[1]appples\n[2]pears\n[3]oranges\n[4]grapes\n[0]exit\n");
	for(i=1;i<=5;i++)
	{
		printf("Enter choice:");
	    scanf("%d",&choice);
	    if(choice==0)
	    break;
	    else
	    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;break;	
		}
		printf("price=%.1lf\n",price);	
	} 
	
	               
	return 0;
}