作业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;
}

 

2.

//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("%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; 
}

 

 

 

 

 

//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("%f,%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>=48&&x<=57) 
    printf("%c是数字字符\n",x);
    else if(x>=65&&x<=90 ||x>=97&&x<=122)
    printf("%c是英文字母\n",x);
    else
    printf("%c是其它字符\n",x);
    
    
    return 0; 
} 

 

 

 

//ex5.cpp
#include <stdio.h>
int main(){
    char ans1, ans2;
    
    printf("复习了没？（输入y或者Y表示复习了，输入n或者N表示没复习） : ");
    ans1 = getchar();
    
    getchar();
    
    printf("敲代码了没？(输入y或者Y表示敲了，输入n或者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;
     
}

 

 

 

 

//等比数列的求和
#include <stdio.h>
#include <math.h>
int main(){
    int n;
    long sum;
    scanf("%d",&n);
    sum =pow(2,n)-1;
    printf("n = %ds时，sum = %d",n,sum);
    
}