实验三

task1.c

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

void print_text(int line, int col, char text[]);//函数声明
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;
}

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);
    }

随机选择当前时间，每次打印都暂停1000ms,在第n行第n列打印"hi,April~"。

task2_1.c

#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;

    p = p * n;
    
    return p;
}

加入一行源代码后：

#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);  //打印P的值 
    p = p * n;
    
    return p;
}

task2_2.c

#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;
}

测试结果一致。

局部变量static是单一变量。

task3.c

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

task4.c

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

task5_1.c

#include <stdio.h>
#include <stdlib.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 , j;
    double A=1.0;
    if(y>=0)
    {for(i=1;i<=y;i++)
       A=A*(x*1.0);}
     else
    {for(i=-1;i>=y;i--)
         A=A/(x*1.0);}
     return A;
}

task5_2.c

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

task6.c

#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 tot;

int main() {
    unsigned int n;
    while (scanf_s("%u", &n) != EOF) {
        tot = 0;
        hanoi(n, 'A', 'B', 'C');
        printf("一共移动了%d次\n", tot);}
    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) {
    tot ++;
    printf("%u:%c-->%c\n", n, from, to);
}

task7.c

#include<stdio.h>
#include<stdlib.h>

int is_prime(int x);

int main() 
{
    int i, n;
    while (scanf_s("%d", &n) != EOF) 
{
    for (i = 2; i <= n; i++) 
    {
     if (!is_prime(i) || !is_prime(n - i))continue;
            printf("%d = %d + %d\n", n, i, n - i);
            break;
    }
}

    return 0;
}

int is_prime(int x) 
{
    int i;
    for (i = 2; i *i<= x; i++) 
{
    if (x % i == 0) 
    {
            return 0;
    }
        else 
    { 
            return 1; 
    }
}
}

task8.c

#include <stdio.h>
#include <math.h>
#include<stdlib.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)
{
    long ans,z=0,q=0,j;

    for(;s!=0;)
{
    ans = s % 10;
    s = s / 10;
    if(ans%2 != 0)
    z = z*10 +ans;    
}
    for(;z!=0;)
{
    j = z % 10;
    z = z/10;
    q = q*10 + j;
}
    return q;
}