实验3

task1:

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#include<windows.h>
#define N 80

void printf_text(int line,int col,char text[]);
void printf_spaces(int n);
void printf_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);
    }
}

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);
}

结论：每隔一秒在屏幕的随机位置打出一个“hi April~”

task2_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! = %lld\n",i,fac(i));
    
    return 0;
}
long long fac(int n) {
    static long long p = 1;
    printf("p = %lld\n",p);
    p = p * n;
    return p;
}

task2_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;
}

结论：在函数内部定义的变量只初始化一次，再次调用这个函数的时候，这个static变量也不会再次被初始化

task3:

#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 = %lld\n",n,f);
        
    }
    return 0;
}
long long func(int n){
    long long f;
if(n == 0)
f = 0;
else
f = 2*func(n-1)+1;

    return f;
}

task4:

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

task5_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 i;
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:

#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 ans = 1.0;
    if(y == 0)
    ans == 1.0;
    else if(y>0)
    ans = x*mypow(x,y-1);
    else
    ans = 1/mypow(x,-y);
    return ans;
}

task6:

#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,t;
    while(scanf("%u",&n)!=EOF){
        t = pow(2,n)-1;
    
    hanoi(n,'A','B','C');
    printf("一共移动盘子%u次\n",t);}
    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:

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

    for(i=2;i <= sqrt(1.0*n);i++)
    {if(n%i==0){
        return 0;break;
    }
    }
    if(n>1&&i>sqrt(1.0*n))
    return 1;
    else
    return 0;
}

task8:

#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 t,n=0,i=0;
    while(s!=0)
    {
        t = s%10;
        if(t%2==1){
            n=n+t*pow(10,i);
            i++;
        }
        s=s/10;
    }
    return n;
}