实验4

实验1

#include <stdio.h>
long long fun(int n);   // 函数声明 

int main() {
    int n;
    long long f;

    while (scanf("%d", &n) != EOF) {
        f = fun(n);
        printf("n = %d, f = %lld\n", n, f);
    }

    return 0;
}
//函数定义
//补足。。。
long long fun(int n) {
    if (n == 1) {
        return 1;
    }
    else {
        return fun(n - 1) * 2 + 1;
    }
}

实验2

#include <stdio.h>
long long fac(int n);  // 函数声明 

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;
}

// 函数定义 
long long fac(int n) {
    static long long p = 1;

    p = p * n;

    return p;
}

#include<stdio.h>
int func(int, int);

int main() {
    int k = 4, m = 1, p1, p2;

    p1 = func(k, m);
    p2 = func(k, m);
    printf("%d,%d\n", p1, p2);

    return 0;
}

int func(int a, int b) {
    static int m = 0, i = 2;

    i += m + 1;
    m = i + a + b;

    return (m);
}

static变量只能在定义该变量的函数内使用

实验3

#include <stdio.h>
#include <stdlib.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 = j;
        for (i = 2; i < j; i++)
            if (flag % i == 0) {
                flag = 0;
                break;
            }
        if (flag != 0)
            bb[k++] = j;
    }
    return k;
}

int main() {
    int n = 0, m = 0, i, k, bb[N];

    scanf("%d", &n);
    scanf("%d", &m);

    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]);

    return 0;
}

实验4

#include <stdio.h>
void dec2n(int x, int n);  // 函数声明 

int main() {
    int x;
    
    printf("输入一个十进制整数: ");
    scanf("%d", &x);
    
    dec2n(x, 2);   // 函数调用: 把x转换成二进制输出 
    dec2n(x, 8);     // 函数调用: 把x转换成八进制输出
    dec2n(x, 16);    // 函数调用: 把x转换成十六进制输出
    
    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]);
    }
}