实验2

//ex1.cpp
#include<stdio.h>
int main(){
    int a=5,b=7,c=100,d,e,f;
    
    d=a/b*c;
    e=a*c/b;
    f=c/b*a;
    
    printf("d=%d,e=%d,f=%d\n",d,e,f);
    
    return 0;
}

//ex2.cpp
#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;
    
}

//ex3.cpp
#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("%lf,%lf\n",x,y);
    
    return 0;
}

//ex4.cpp
//判断字符类型
#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是其他字符\n",x);
    
    return 0;
} 

//ex5.cpp
#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'||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;
}

//ex6.cpp
#include <stdio.h>
#include <math.h>
int main(){
    
    int a,n;
    
    scanf("%d",&n);
    a=(1-pow(2,n))/(-1);
    printf("n=%d时，sum=%d",n,a);
    
    return 0;
}