作业4

#include<stdio.h>
 2 long long fun(int n);
 3 
 4 int main(){
 5     int n;
 6     long long f;
 7     
 8     while(scanf("%d", &n) != EOF){
 9         f = fun(n);
10         printf("n = %d, f = %lld\n", n, f);
11     }
12     
13     return 0;
14 }
15 
16 long long fun(int n){
17     if(n == 1)
18     return 1;
19     else
20     return 2*(fun(n-1)+1)-1;
21 }

#include<stdio.h>
long long fac(int n);
  
int main(){
    int i, n;
    
    printf("Enter n:");
    scanf("%d", &n);
    
    for(i=1;i<=n;++i)
          printf("%d! = %lld\n", i, fac(i));
        
    return 0;
}
 
long long fac(int n){
    static long long p = 1;
    
    p = p*n;
    
    return p;
}

#include<stdio.h>
#define N 1000

int fun(int n, int m,int bb[N]) {
    int i, j, k=0,flag;
    
    for(j=n;j<=m;j++){
        flag = 1;
        for(i=2;i<j;i++)
        if(j % i == 0){
            flag = 0;
            break;    
        }
        if(flag == 1)
        bb[k++] = j;    
    }
    return k;
}
  
int main(){
    int n=0, m=0, i, k, bb[N];
    
    while(scanf("%d %d",&n, &m) != EOF){
    

    
    for(i=0;i<m-n;i++)
        bb[i] = 0;
        
    k=fun(n,m,bb);
    
    for(i=0;i<k;i++)
        printf("%4d",bb[i]);
        printf("\n");
}
        
    return 0;
}

#include <stdio.h>
void dec2n(int x, int n);  
int main() {
    int x;
    
    printf("输入一个十进制整数: ");
    scanf("%d", &x);
    
    dec2n(x, 2);  
    dec2n(x, 8);     
    dec2n(x, 16);    
    
    return 0;
}
void dec2n(int x, int n) {
    int i, b, a[100];
    
       for(i=0;x!=0;i++){
       a[i]=x%n;
       x=x/n;
       }
    if(a[i]>9)  
       switch(a[i]){
       case 10:a[i]='A';break;
       case 11:a[i]='B';break;
       case 12:a[i]='C';break;
       case 13:a[i]='D';break;
       case 14:a[i]='E';break;
       case 15:a[i]='F';break;
       }
    printf("\n");
    for(b=i-1;b>=0;b--){
        printf("%d",a[b]);
    }
}