实验3

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_blank_lines(int n); 
int main() {
    int line, col, i;
    char text[N] = "hi, April~";
    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); 
}

 

代码作用：

以系统时间为随机种子生成随机数，打印随机空格和换行，并打印字符串，进行十次

 

 

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); // 函数声明
int main() {
int k = 4, m = 1, p1, p2;
p1 = func(k, m); // 函数调用
p2 = func(k, m); // 函数调用
printf("%d, %d\n", p1, p2);
return 0;
}
// 函数定义
int func(int a, int b) {
static int m = 0, i = 2;
i += m + 1;
m = i + a + b;
return m;
}

 运行结果与我判断一致

 

总结局部static变量特点：

1.局部性，该变量只能作用于定义其的函数或复合语句中，只有在函数内部有效，离开函数就不能再被使用

2.静态存储，该变量在程序运行期间有系统分配固定的存储空间，当再次进入函数时，使用上次的结果，即具有继承性

 

 

task3.c

 

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

 

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 ans;
    if (n == m) ans = 1;
    else if (m == 1) ans = n;
    else if (n == 0) ans = 0;
    else
        ans = func(n - 1, m) + func(n - 1, m - 1);
    return ans;
}

 

 

task5_1.c

 

#include <stdio.h>
double mypow(int x, int y); // 函数声明
int main() {
    int x, y;
    double ans;
    while (scanf_s("%d%d", &x, &y) != EOF) {
        ans = mypow(x, y); // 函数调用
        printf("%d的%d次方: %g\n\n", x, y, ans);
    }
    return 0;
}
double mypow(int x, int y) {
    int i ,j;
    double ans=1.0;
    if (y >= 0)
    {
        for (i = 1; i <= y; i++)
            ans = ans * x;
    }
    else
    {
        for (i = 1; i <= ( - y); i++)
            ans = ans / x;
    }
    return ans;
}

 

 

task5_2.c

 

#include <stdio.h>
double mypow(int x, int y); // 函数声明
int main() {
    int x, y;
    double ans;
    while (scanf_s("%d%d", &x, &y) != EOF) {
        ans = mypow(x, y); // 函数调用
        printf("%d的%d次方: %g\n\n", x, y, ans);
    }
    return 0;
}
double mypow(int x, int y) {
    double ans;
    if (y == 0) ans = 1;
    else if (y > 0) ans = x * mypow(x, y - 1);
    else ans = 1.0 / mypow(x, (-y));
    return ans;
}

 

 

 

task6.c

 

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

void hanoi(unsigned int n, char from, char temp, char to);
void moveplate(unsigned int n, char from, char to);
int t = 0;
int main() {
    unsigned int n;
    while ((scanf_s("%u", &n)) != 0)

    {
        hanoi(n, 'A', 'B', 'C');
        printf("\n\n一共移动了%d次", t);
    }

    
    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);
    t = t + 1;
}

 

 

tsak7.c

 

 

#include <stdio.h>
int is_prime(int );
int main() {
    int i, j;

    for (j = 4; j <= 20; j += 2)
    {
        for (i = 2; i <= j / 2; i++)
        {
            if (is_prime(i) && is_prime(j - i))
            {
                printf("%d=%d+%d\n", j, i, j - i);
                break;
            }
        }    
    }
    return 0;

}
int is_prime(int n) {
    int i = 2, t;

    for (; n % i != 0 && i <= n; )
    {
        i++;
    }
    if (n == i)
        t = 1;

    else
        t = 0;

    return (t);



        
}

 

 

 

task8.c

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

    }
    return n;
    
}