实验二

#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!"; // 定义一个字符型数组a,数组中存放字符串常量
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("%f,%lf",&x,&y);
printf("%f,%lf\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(×××) 
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>=‘a‘)&&(x<=‘z‘)) 
printf("%c是英文字母\n", x);
else if( (x>=‘0‘)&&(x<=‘9‘)) 
printf("%c是数字字符\n", x);
else
printf("%c是其它字符\n", x);
return 0;
}

#include<stdio.h>
#include<math.h>
int main() {
        int sum,i,n;
        double q;
        q=2,i=0,sum=0;
        scanf("%d",&n);
        while(i<=n)
        {
        sum=pow(q,i)+sum;
        i++;
        }
        printf("n=%d时，sum=%d\n",n,sum);
        return 0;
}