实验三

task1

#include <stdio.h>#include <stdlib.h>#include <time.h>#include <windows.h>#define N 80void printText(int line, int col, char text[]); // 函数声明void printSpaces(int n); // 函数声明void printBlankLines(int n); // 函数声明int main(){int line, col, i;char text[N] = "hi, May~";srand(time(0)); // 以当前系统时间作为随机种子for(i=1; i<=10; ++i){line = rand()%25;col = rand()%80;printText(line, col, text);Sleep(1000); // 暂停1000ms}return 0;}void printSpaces(int n){int i;for(i=1; i<=n; ++i)printf(" ");}void printBlankLines(int n){int i;for(i=1; i<=n; ++i)printf("\n");}void printText(int line, int col, char text[]){printBlankLines(line-1);printSpaces(col-1); printf("%s", text);}

功能：在屏幕上 25行，80列 的范围内任意位置打印十次字符串”hi,May~“，每次打印间隔1000ms

task2-1

// 利用局部static变量的特性，计算阶乘#include <stdio.h>long long fac(int n); // 函数声明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;}// 函数定义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); // 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;}

局部static的特性：在局部变量前面加关键字 static 进行声明，该变量就是一个 static 局部变量。static 局部变量 的特点是它位于静态存贮区，在函数调用结束后，它的值仍然存在，并可能影响到下一次调 用的过程。

task3

#include <stdio.h>long long fun(int n); int main(){int n;long long f;while (scanf("%d", &n) != EOF){f = fun(n); printf("n = %d, f = %lld\n", n, f);}return 0;}long long fun(int n){int i;long long a=0,p=1;if(n==0) a=1;else {    for(i=1;i<=n;i++)    {        p=p*2;    }    a=p-1;}return a;}

task 4

#include<stdio.h>#include<stdlib.h>int i;void hanoi(unsigned n,char from,char to,char temp);void move(unsigned n,char from,char to);int main(){   unsigned n;while(scanf("%u",&n)!=EOF){    i=0;    hanoi(n,'A','C','B');printf("一共移动了%d次",i);}system("pause");}void hanoi(unsigned n,char from,char to,char temp){if(n==1)move(n,from,to);else{hanoi(n-1,from,temp,to);move(n,from,to);hanoi(n-1,temp,to,from);}}void move (unsigned n,char from,char to){   i++;printf("%u:%c-->%c\n",n,from,to);}

task 5

#include<stdio.h>#include<stdlib.h>#include<math.h>int is_prime(int n);int main(){int n,p,q,flagp,flagq;              for(n=4;n<=20;n+=2){    p = 1;    do    {        p++;        q=n-p;        flagp=is_prime(p);        flagq=is_prime(q);    	}     while(flagq*flagp == 0);    printf("%d =%d + %d\n", n, p, q);}return 0;}int is_prime(int n){int k;for(k=2;k<=sqrt(n);k++)    if(n%k==0)    {        return 0;    }    return 1;    }

task 6

#include<stdio.h>#include<stdlib.h>long fun(long s);int main(){  	long s,t;printf("Enter a number:");while(scanf("%ld",&s) != EOF){    t=fun(s);    printf("new number is:%ld\n\n",t);    printf("Enter a number:");}system("pause");}long fun(long s){    long i,p,t=0,x=0,m;p=s;while(p!=0){        i=p%10;if(i%2==1)t=t*10+i; p/=10; }while(t!=0){    m=t%10;x=x*10+m;t/=10;}return x;}