实验四

#include <stdio.h>
long long fun(int n); 
int main()
 {
  int n;
  long long f;
  while(scanf("%d", &n) != EOF)
 {
  f = fun(n); // 函数调用
  printf("n = %d, f = %lld\n", n, f);
 }
  return 0;
 }
 long long fun(int n) {
 
 long long s;
 if(n==1)
 return 1;
 else{
 s=2*fun(n-1)+1;
 return s;}
 }

#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 m,p;
    char a[100];
    for(m=0;x!=0;m++){
        a[m]=x%n;
        x=x/n;
    }
    if(a[m]>9)
    switch(a[m]){
       case 10:a[m]='A';break;
       case 11:a[m]='B';break;
       case 12:a[m]='C';break;
       case 13:a[m]='D';break;
       case 14:a[m]='E';break;
       case 15:a[m]='F';break;
    }
    for(p=m-1;p>=0;p--)
    printf("%X",a[p]);
     printf("\n");
    
}