实验2

#include<stdio.h>
int main(){
    int num;
    
    scanf("%d",&num);
    printf("2049%04d\n",num);
    
    scanf("%d",&num);
    printf("2049%04d\n",num);
    
    scanf("%d",&num);
    printf("2049%04d\n",num);
    
    return 0;
    
    

} 

#include<stdio.h>
int main(){
    int x=1234;
    float f=123.456;
    double m=123.456;
    char ch='a';
    char a[]="Hello,world!";
    int y=3,z=4;
    
    printf("%d %d\n",y,z);
    printf("y=%d,z=%d\n",y,z);
    printf("%8d,%2d\n",x,x);
    printf("%f,%8f,%8.1f,%0.2f,%.2e\n",f,f,f,f,f);
    printf("%1f\n",m);
    printf("3c\n",ch);
    printf("%s\n%15s\n%10.5s\n%2.5s\n%.3s\n",a,a,a,a,a);
    
    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%c\n",c1,c2,c3);
    scanf("%1f,%1f",&x,&y);
    printf("%1f,%1f\n",x,y);
    
    return 0;
}

#include<stdio.h>
int main(){
    char ans1,ans2;
    
    printf("复习了没？（输入y或y表示复习了，输入n或N表示没有复习）:");
    ans1=getchar();
    
    getchar();
    
    printf("\n动手敲代码了没？(输入y或Y表示敲了，输入n或N表示木有敲):");
    ans2=getchar();
    
    if((ans1=='y'||ans1=='Y')&&(ans2=='y'||ans2=='Y'))
        printf("\n罗马不是一天建成的:)\n");
    else
        printf("\n罗马不是一天毁灭的。。。\n");
        
        return 0;
     
}

#include<stdio.h>
int main(){
    char x;
        
    x=getchar();
    
    if(x>='0'&&x<='9')
        printf("%c是数字字符\n",x);
    else if(x>='a'&&x<='z'||x>='A'&&x<='Z')
        printf("%c是英文字母\n",x);
    else
        printf("%c是其它字符\n",x);
        
        
        return 0;
}

#include <stdio.h>
int main() {
    int n,sum,s,m;
    sum=1;
    s=1;
    m=1;
    scanf("%d",&n);
    while(m<=n){
        s=s*2;
        m=m+1;
        sum=sum+s;    
    }
    printf("n等于%d时，sum=%d",n,sum);
    return 0;
}