实验三

task.1

#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);
    }
    
    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);
} 

作用：在空（line-1）行，空（col-1)列的一个随机位置打印“hi，April~”这个字符，整个过程持续1000ms

task.2.1

#include<stdio.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! =%11d\n", i ,fac(i));
    
    return 0;
} 

long long fac(int n){
    static long long p = 1;
    
    p=p*n;
    printf("p = %11d\n" ,p);
    return p;
}

task.2.2

#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特性：在一个函数被调用结束后不清空内部的赋值，而是保存下来，等待下一次被使用

task.3

#include<stdio.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=%11d\n", n, f);
    }
    return 0;
} 
long long func(int n){
    int i,t,m;
    t=2;
    m=2;    
    for(i = 1; i < n; i++){
        m*=t;
    }
    m=m-1;
    return m;
}

task.4

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

task.5.1

#include <stdio.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);   
    }

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

task.5.2

#include <stdio.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);   
    }

    return 0;
} 

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

task.6

#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 cnt=0;
int main(){
    unsigned int n;
    while(scanf("%u" , &n) != EOF){
    hanoi(n,'A','B','C');
    printf("一共移动了%d次\n",cnt);
    cnt=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);
    cnt++;
}

task.7

#include<stdio.h>
#include<math.h>
int is_prime(int);
int main(){
    int yuanshu;
    int i;
    while(scanf("%d", &yuanshu)!=EOF){
    for(i = 2;;i++){
        if(is_prime(i)==1){
        if(is_prime(yuanshu-i)==1){
            printf("%d=%d+%d",yuanshu,i,yuanshu-i);
            break;
        }
    }
    }
}
    return 0;
} 

int is_prime(int x){
    int i,m;
    m=1;
    for(i = 2;i<=sqrt(x);i += 1){
        if(x%i==0){
            m=0;
            return 0;
        }
    }
    return 1;
}

task.8

#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("new number is: %ld\n\n", t);
        printf("Enter a number: ");
    }
    return 0;
}

long func(long s){
    int n=0;
    int sum=0;
    while(s!=0){
        n=n*10+s%10;
        s=s/10;
    }
    int a;
    while(n!=0){
        a=n%10;
        if(a%2!=0){
            sum=sum*10+a;
        }
        n=n/10;
    }
    return sum;
}