实验2

part1:
#include <stdio.h>
int main() {
	int x=1234;
	float f=123.456;
	double m=123.456;
	char ch=‘a‘;
	char a[]="Hello, world!"; // 定义一个数组a,数组中连续存放了字符串常量hello,world!
	int y=3, z=4; 
	printf("%d %d\n", y, z);  //一致
	printf("y=%d, z=%d\n", y,z);  //一致
	printf("%8d,%2d\n", x,x);  //一致
	printf("%f, %8f, %8.1f, %0.2f, %.2e\n",f,f,f,f,f);  //不一致，计算机把float型数据转换为能识别的二进制数时，不能完全转化，会舍去一部分数值，所以在输到电脑上时，
                                                                  就会不一样
	printf("%lf\n",m);   //一致
	printf("%3c\n", ch);  //一致
	printf("%s\n%15s\n%10.5s\n%2.5s\n%.3s\n",a,a,a,a,a);  //一致
	return 0;
}

#include <stdio.h>
int main() {
	double x,y;
	char c1,c2,c3;
	int a1,a2,a3;
	scanf("%d%d%d",&a1,&a2,&a3);
	printf("%d,%d,%d\n",a1,a2,a3);
	scanf("%c%c%c",&c1,&c2,&c3);
	printf("%c%c%c\n",c1,c2,c3);
	scanf("%lf,%lf",&x,&y);
	printf("%f,%lf\n",x,y);
	return 0;
} 

#include <stdio.h>
#include <stdlib.h>
int main() {
	int choice;
	
	// 显示菜单 
	printf("输入0~9以内的数字，选择屏幕背景色前景色方案: \n");
	printf("1-\t黑底绿色\n");
	printf("2-\t白底黑色\n");
	printf("3-\t蓝底白色\n");
	printf("其它-\t黑底白色(默认)\n");
	printf("\n请输入, 选择你想使用的屏幕配色方案:    ");
	
	// 要求用户从键盘输入0~9的数字，选择屏幕配色方案 
	scanf("%d",&choice);
	
	// 根据用户输入，设置屏幕配色方案 
	if (choice ==1) {
		system("color 02");
		printf("《黑客帝国》一类的影视剧常见这种屏幕色:)\n"); 
	} 
		
	else if(choice ==2) {
		system("color f0");
		printf("大部分编辑器默认是这种配色:)\n");	
	}
		
	else if(choice ==3) {
		system("color 1f");
		printf("这是机器蓝屏故障时的不讨喜色:)\n");
	}
		
	else {
		system("color 0f");
		printf("控制台程序默认小黑窗:)\n");		
	}
		
		
	printf("programming is fun, just try@_@\n");
	
	
	return 0;
} 

# include<stdio.h>
int main() {
	int x;
	printf("输入数字:\n");
	scanf("%d",&x);
	if(x/100==0)
	 { if(x/10==0)
	    printf("正序和逆序相同\n");
		else if(x/10+x%10*10==x)
		printf("正序和逆序相同\n");
		 else
		  printf("正序和逆序不相同\n");
	 }
	else if(x==x/100+x%100%10*100+x%100/10*10

# include<stdio.h>
# include<stdio.h>
int main(){
	int year,month,day,leapyear;
	scanf("%d%d",&year,&month);
	if(year<0||month<1||month>12)
		printf("输入的数据错误！\n");
	else if(leapyear=year%4==0&&year%100!=0||year%400==0){
	      printf("是闰年");
		   
			if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
		        {  day=31;
		           printf("%d年%d月的天数为：%d\n",year,month,day);
		           return 0;
		        }
		    else if(month==4||month==6||month==9||month==11)
		        {day=30;
		        printf("%d年%d月的天数为：%d\n",year,month,day) ;
		          return 0;
				}
			else
			      {
				    day=28+leapyear;
			        printf("%d年%d月的天数为：%d\n",year,month,day);
				    return 0; }
		}
	else 
	{
     	printf("是平年");
		if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
		        {  day=31;
		           printf("%d年%d月的天数为：%d\n",year,month,day);
		           return 0;
		        }
		    else if(month==4||month==6||month==9||month==11)
		        {day=30;
		        printf("%d年%d月的天数为：%d\n",year,month,day) ;
		          return 0;
				}
			else
			    {day=28+leapyear;
			     printf("%d年%d月的天数为：%d\n",year,month,day);
				 return 0;  
	            }
	        return 0;
	    }
	} 

#include<stdio.h>
int main(){
	int x;
	printf("输入分数:\n");
	scanf("%d",&x);
	if(x<0||x>100){
	 printf("分数不在有效区间内");
	 }
	switch(x/10) {
	case 9:printf("优秀\n");break;
	case 8:printf("良好\n");break;
	case 7:printf("中等\n");break;
	case 6:printf("及格\n");break;
	default:printf("不及格\n");break;
               }
    return 0;
}

) printf("正序和逆序相同\n"); else printf("正序和逆序不相同\n"); return 0;}