实验三

task1.c

#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); 
}

功能：在25行/80列的空间里任意位置处打印出"hi, November~"，停留一秒，在下一个25行/80列的空间里重复上述操作，如此共重复10次。

task2_1.c

#include <stdio.h>
long long fac(int n); 
int main() {
    int i, n;
    printf("Enter n: ");
    scanf_s("%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;
}

task2_2.c

#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;
}

局部变量static的特性：能将static所在的函数运行一次后的结果保留，并用于下一次函数的运行。

task3.c

#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) {
    double result;
    if (n == 1)
        result = 1;
    else
        result = 2 * func(n - 1) + 1;
    return result;
}

task4.c

#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) {
    int result;
    if (n == m || m == 0)
        result = 1;
    else if (n < m)
        result = 0;
    else
        result = func(n - 1, m) + func(n - 1, m - 1);
    return result;
}

task5.c

#include <stdio.h>
#include<stdlib.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) {
    int result;
    if (n == 0 || m == 0) {
        result = 0;
    }
    else if (n > m) {
        result = mul(n, m - 1) + n;
    }
    else {
        result = mul(n - 1, m) + m;
    }
    return result;
}

task6.c

 

#include< stdio.h>
#include<stdlib.h>
#include<math.h>
void hanoi(unsigned int n, char from, char temp, char to);
void moveplate(unsigned int n, char from, char to);

int main()
{
    unsigned int n;
    int m;
    
    while (scanf_s(" %u", &n) != EOF) {
        hanoi(n, 'A', 'B', 'C');
        m = pow(2, n) - 1;
        printf("一共移动了%d次.\n", m);
        system("pause");
    }
    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);
    
}

task7.c

#include< stdio.h>
#include<stdlib.h>
#include<math.h>
int is_prime(int n);
int main() {
    int m;
    while (scanf_s("%d", &m) != EOF)
        is_prime(m);
    return 0;
}
int is_prime(int n) {
    int i, p_flag, q_flag,p,q;
    
    if ((n % 2 == 1) || n < 4) {
        printf("数据输入错误\n");
        exit (0);
    }
    p = 1;
    do
    {
        p += 1;
        q = n - p;
        p_flag = 1;
        for (i = 2; i <= sqrt(1.0 * p); i++) 
        {
            if (p % i == 0) 
            {
                p_flag = 0;
                break;
            }
        }
        q_flag = 1;
        for (i = 2; i <= sqrt(1.0 * q); i++)
        {
            if (q % i == 0) 
            {
                q_flag = 0;
                break;
            }
        
        }

    } while (p_flag * q_flag == 0);
    printf("%d = %d + %d", n, p, q);
    
}

task8.c

#include <stdio.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) {
    long n, result = 0;
    int m = 1;
    while (s > 0)
    {
        n = s % 10;
        if (n % 2 != 0)
        {
            result += n * m;
             m *= 10;
        }
        s = s / 10;
    }
    return result;
}