实验3

task1

#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);
    }
    system("pause");
    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);}

以时间为随机种子在屏幕随机行列打印November~，并重复执行。

task2

#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;
}
int func(int a ,int b){
    static int m=0,i=2;
    i+=m+1;
    m=i+a+b;
    return m;}

一致

局部静态变量，只能被初始化一次，二次初始无效。

task3

#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){
    long long ans;
    if (n==0)
        ans=0;
    else{
        ans=func(n-1)*2+1;}
return ans;}

task4

#include<stdio.h>
#include<stdlib.h>
long long 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));
    system("pause");
    return 0;
}
long long func(int n,int m){
    long long ans;
    if(m>n||n==0)
        return 0;
    else if (m==n||m==0)
        return 1;
    else if(m==1)
        return n;
    else if(m<n&&m!=1)
        return ans=func(n-1,m)+func(n-1,m-1);}

task5

#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));
    system("pause");
    return 0;
}
int mul(int n,int m){
    long ans=0;
    int t;
    if(m>n)
        t=m,m=n,n=t;
    if(m==0)
    return ans=0;
    return    ans+=mul(n,m-1);}

task6

#include<stdio.h>
#include<stdlib.h>
void hanoi(unsigned n,char from,char temp,char to);
void moveplate(unsigned n,char from,char to);
long count=0;
int main()
{
   unsigned n;
  while( scanf_s("%u",&n)!=EOF)
{   hanoi(n,'A','B','C');
  printf("一共移动了%ld次\n",count);}
system ("pause");
return 0; }
void hanoi(unsigned 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 n,char from,char to)
{printf("%u:%c-->%c\n",n,from,to);
  count++;
}

task7

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
int is_prime(int n);
int main(){
    int n,k;
    while(scanf_s("%d",&n)!=EOF)
    {    if(n%2!=0)
            printf("illegal\n");
      else
        for(k=2;k<=n-k;k++)
            {
             if (is_prime(k)&&is_prime(n-k))
             { printf("%d = %d + %d\n",n,n-k,k);}}
    }
    system("pause");
    return 0;
}
int is_prime(int n){
    int i;
    double m;
    m=pow(n,0.5);
    for(i=2;i<=m;i++)
        if(n%i==0)break;
        
    if(i>m&&n!=1)
        return 1;
    else
        return 0;}

task8

#include<stdio.h>
#include<stdlib.h>
#include<math.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 munber is:%ld\n\n",t);
        printf("Enter a number: ");}
    system("pause");
    return 0;
}
long fun(long s){
    long ans,num=0;
    int h=1;
    while(s>0)
        { ans=s%10;
        if(ans%2!=0)
        {
            num+=ans*h;
            h=h*10;
        }
        s=s/10;
        }
    return num;}