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 num;
    int x;
    do
    {
        scanf("%d", &num);
        printf("2049%04d\n", num);
        x = x++;
    
    } while (x<4);
    
    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("%lf\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\n",c1,c2,c3);
    scanf("%lf,%lf",&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‘||‘Y‘)&&(ans2=‘y‘||‘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‘) 
            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,x,y;
    sum = 1;
    x = 1;
    y = 2;
    scanf("%d",&n);
    do
    {
        sum += y;
        y = y * 2;
        x++;

    } while (x<=n);
    printf("n=%d时,sum=%d\n", n, sum);
    return 0;
}