实验三

实验三

实验任务1

程序源码

#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, April";

    srand(time(0));

    for(i = 1; i <= 10; ++i){
        line = rand() % 25;
        col = rand() % 80;
        print_text(line, col, text);
        Sleep(1000);
    }

    system("pause");
    return 0;

}

//打印n个空格
void print_spaces(int n){
    int i;

    for(i = 1; i <= n; ++i)
        printf(" ");
}

//打印n行空白行
void print_blank_lines(int n){
    int i;

    for(i = 1; i <= n; ++i)
        printf("\n");
}

//在第line行第col列打印一段文本
void print_text(int line, int col, char text[]){
    print_blank_lines(line-1);
    print_spaces(col-1);
    printf("%s", text);
}

程序运行截图

讨论：在0~24行，0~79列中随机选一行一列，在第line行打印（line-1）行空行，第col列打印（col-1）列空格，在第line行第col列输出“hi, April”，重复运行10次，每次间隔1000ms

实验任务2

程序源码

//利用局部static变量的特性，计算阶乘

#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));

    system("pause");
    return 0;
}

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

    p = p * n;

    return p;
}

程序运行截图

程序源码

//利用局部static变量的特性，计算阶乘

#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));

    system("pause");
    return 0;
}

//函数定义
long long fac(int n){
    static long long p = 1;
    printf("p = %lld\n", p);

    p = p * n;

    return p;
}

程序运行截图

实验源码

//练习局部static变量特性

#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);

    system("pause");
    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;
}

实验运行截图

讨论：

实验任务3

程序源码

#include<stdio.h>
#include<stdlib.h>
long long func(int n);

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

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

    system("pause");
    return 0;

}

long long func(int n){
    if(n == 1){
        return 1;
    }
    return 2 * func(n - 1) + 1;
}

程序运行截图

讨论：

实验任务4

程序源码

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

int main(){
    int n, m;

    while(scanf("%d%d", &n, &m) != EOF)
        printf("n = %d, m = %d, ans = %d\n", n, m, func(n, m));

    system("pause");
    return 0;

}

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

程序运行截图

讨论：

实验任务5

程序源码

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
double mypow(int x, int y);

int main(){
    int x, y;
    double ans;

    while(scanf("%d%d", &x, &y) != EOF){
        ans = mypow(x, y);
        printf("%d的%d次方：%g\n\n", x, y, ans);
    }

    system("pause");
    return 0;

}

double mypow(int x, int y){
    if(y == 0){
        return 1;
    }
    else if(y > 0){
        return mypow(x, y - 1) * x;
    }
    else if(y < 0){
        return (double)mypow(x, y + 1) / (double)x;
    }
}

程序运行截图

程序源码

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
double mypow(int x, int y);

int main(){
    int x, y;
    double ans;

    while(scanf("%d%d", &x, &y) != EOF){
        ans = mypow(x, y);
        printf("%d的%d次方：%g\n\n", x, y, ans);
    }

    system("pause");
    return 0;

}

double mypow(int x, int y){
    int i,j;
    double ans=1;
    if(y>=0)
        for(i=1;i<=y;i++)
            ans=ans*x;
    else{
        for(j=1;j<=(-y);j++)
            ans=ans*x;
        ans=1.0/ans;
    }
    return ans;
}

程序运行截图

讨论：

实验任务6

程序源码

#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 a=0;
    while(scanf("%u",&n)!=EOF){
        hanoi(n,'A','B','C');
        printf("\n");
        a=pow(2,n)-1;
        printf("一共移动了%d次\n\n",a);
    }
    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);
}

程序运行截图

讨论：

实验任务7

程序源码

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
int is_prime(int n);

int main(){
    int j,k;
    while(scanf("%d",&j)!=EOF){
        for(k=1;k<=j;k++)
            if(is_prime(k)&&is_prime(j-k))break;
        printf("%d=%d+%d\n",j,k,j-k);
    }
    return 0;
}

int is_prime(int n){
    int i;
    double m;
    m=sqrt(n);
    for(i=2;i<=m;i++)
        if(n%i==0)break;
    if(n!=1&&i>m)
        return 1;
    else
        return 0;
}

程序运行截图

讨论：

实验任务8

程序源码

#include<stdio.h>
#include<math.h>
long func(long s);

int main(){
    
    long s,t;
    printf("Enter a number:");
    while(scanf("%ld",&s)!=EOF){
        t=func(s);
        printf("nem number is: %ld\n\n",t);
        printf("Enter a number:");
    }
    
    return 0;
} 

long func(long s){
    long b=0,t=0;
    int a,m;
    while(s!=0){
        a=s%10;
        if(a%2!=0)
            b=10*b+a;
        s=s/10;
    }
    
    while(b!=0){
        m=b%10;
        t=10*t+m;
        b=b/10;
    }
    
    return t;
}

程序运行截图

讨论：