实验三

实验任务一

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <windows.h>
#define N 80
void print_text(int line, int col, char text[]);
void print_spaces(int n);
void print_blank_lines(int n);
int main() {
    int line, col, i;
    char text[N] = "hi, November~";
    srand(time(0));
    for (i = 1; i <= 10; ++i) {
        line = rand() % 25;
        col = rand() % 80;
        print_text(line, col, text);
        Sleep(1000);
    }
    return 0;
}
void print_spaces(int n) {
    int i;
    for (i = 1; i <= n; ++i)
        printf(" ");
}
void print_blank_lines(int n) {
    int i;
    for (i = 1; i <= n; ++i)
        printf("\n");
}
void print_text(int line, int col, char text[])
{
    print_blank_lines(line - 1);
    print_spaces(col - 1);
    printf("%s", text);
}

实现"hi,November~"的动态滚动效果

实验任务二

2-1

#include <stdio.h>
#include <stdlib.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;
}

2-2

#include <stdio.h>
#include <stdlib.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;
}

局部static变量仅作用于定义的函数内，且变量值只在开始时初始化一次。

实验任务三

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

实验任务四

#include <stdio.h>
int func(int n, int m);
int main() {
    int n, m;
    while (scanf_s("%d%d", &n, &m) != EOF)
        printf("n = %d, m = %d, ans = %d\n", n, m, func(n, m));
    return 0;
}
int func(int n, int m)
{
    if (n < m)
    {
        return 0;
    }
    if (m == 0)
    {
        return 1;
    }
    if (m >= 1)
    {
        return func(n - 1, m) + func(n - 1, m - 1);
    }
}

 实验任务五

#include <stdio.h>
int mul(int n, int m);
int main() 
{
    int n, m;
    while (scanf_s("%d%d", &n, &m) != EOF)
        printf("%d * %d = %d\n", n, m, mul(n, m));
    return 0;
}
int mul(int n, int m)
{
    if (n == 0 || m == 0)
    {
        return 0;
    }
    else
    {
        return mul(n - 1, m) + m;
    }
}

实验任务六

#include<stdio.h>
#include<stdlib.h>
void hanoi(unsigned int n, char ftom, char temp, char to);
void moveplate(unsigned int n, char from, char to);
int count;
int main()
{
    unsigned int n;
    while (scanf_s("%u", &n) != EOF)
    {
        hanoi(n, 'A', 'B', 'C');
        printf("一共移动了%d次", count);
        count = 0;
    }
    return 0;
}

void hanoi(unsigned int n, char from, char temp, char to) {
    if (n == 1)moveplate(n, from, to);
    else {
        hanoi(n - 1, from, to, temp);
        moveplate(n, from, to);
        hanoi(n - 1, temp, from, to);
    }
}
void moveplate(unsigned int n, char from, char to)
{
    printf("%u:%c --> %c\n", n, from, to);
    count++;
}

实验任务七

#include <stdio.h>
#include<math.h>
#include<stdlib.h>
int is_prime(int n);
    int main()
    {
        int a,b;
        int stop = 0;
        int i = 2;
        while (i < 20)
        {
            i += 2;
            for (int a = 2; a < i; a++)
            {
                b = i - a;
                if (is_prime(a)&&is_prime(b))
                {
                    printf("%d = %d+%d\n", i, a, b);
                    stop = 1;
                }
                if (stop) break;
            }
            stop = 0;
        }
        return 0;
    }
    int is_prime(int n)
    {
        if (n == 1) return 0;

        for (int k = 2; k < n; k++)
        {
            int stop = 0;
            if (n % k == 0)
            {
                return 0;
                stop = 1;
            }
            if (n == 2 || (n % k != 0 && k == n - 1)) return 1;
            if (stop) break;
        }
    }

实验任务八

#include <stdio.h>
#include<math.h>
long fun(long s);
int main() {
    long s, t;
    printf("Enter a number: ");
    while (scanf_s("%ld", &s) != EOF) {
        t = fun(s);
        printf("new number is: %ld\n\n", t);
        printf("Enter a number: ");
    }
    return 0;
}
long fun(long s)
{
    int n;
    int i=0;
    int j=0;
    while(s != 0)
    {
        n = s % 10;
        if (n % 2 ==1)
        {
            i = n * pow(10, j) + i;
            j++;
        }
        s /= 10;
    }
    return i;
}