实验三

//生成N个0~99之间的随机整数，并打印输出
#include<stdio.h> 
#include<stdlib.h>
#include<time.h>
#define N 5

int main(){
    int x,n;
    
    srand(time(0));
    
    for(n=1;n<=N;n++) {
        x = rand() % 100;
        printf("%3d",x);
    }
    
    printf("\n");
    
    return 0;
}

//生成0~31之间的随机整数，并打印输出
#include<stdio.h> 
#include<stdlib.h>
#include<time.h>
#define N 5

int main(){
    int x, n;
    
    srand(time(0));
    
    for(n=1;n<=N;n++) {
        x = rand() % 32;
        printf("%3d", x); 
        
    }
    
    printf("\n");
    
    return 0;
}

#include<stdio.h> 
#include<stdlib.h>
#include<time.h>
#define N 1

int main(){
    int x, n, a;
    srand(time(0));
    printf("猜猜2021年5月哪一天会是你的 luck day\n");
    printf("你有三次机会哦，快来是试一试（1~31）:");
    x = rand() % 31+1;
    for(n=1;n<=3;)
    {
        scanf("%d",&a);
        if (a == x)
        {
            printf("猜对啦！！ \n");break;
        }
        else if (a > x)
        {
            printf("你猜的幸运日晚了，lucky day悄悄溜到前面啦\n");
        }
        else
        {
            printf("你猜的幸运日早了，lucky day还没到呢\n");
        }
        n++; 
        if (n > 3)
        {
            printf("次数用完啦，偷偷告诉你幸运日其实是%d啦\n",x);
        }
    }
    return 0;
}

#include<stdio.h>
int main()
{
    long a,b,x;
    printf("Enter your number:"); 
    while(scanf("%ld", &a)!=EOF)
    {
        int n=1;
        x = a;
        while (x /= 10)
              n *= 10;
         while (a)
         {
              if ((b = a / n) % 2 != 0)
                (x *= 10) += b;
                a %= n;
                n /= 10;
        }
        printf("New number is:%ld\n", x);
            printf("Enter your number:"); 
    } 
    return 0;
}

//一元二次方程求解（函数实现方式）
//重复执行，直到按下Ctrl+Z结束

#include<math.h> 
#include<stdio.h>

void solve(double a,double b,double c);
int main(){
    double a, b, c;
    
    printf("Enter a, b, c:") ;
    while(scanf("%1f%1f%1f",&a, &b, &c) !=EOF){
        solve(a, b, c);
        printf("Enter a, b, c:");
    }
    
    return 0;
}

void solve(double a, double b, double c){
    double x1, x2;
    double delta, real, imag;
    
    if(a == 0)
      printf("not quadratic equation.\n");
    else{
        delta = b*b - 4*a*c;
        
        if(delta>=0){
           x1 = (-b + sqrt(delta)) / (2*a);
           x2 = (-b - sqrt(delta)) / (2*a);
           printf("x1 = %.2f,x2 = %.2f\n, x1, x2");
        } 
        else{
            real = -b/(2*a);
            imag = sqrt(-delta) / (2*a);
            printf("x1 = %.2f + %.2fi, x2 = %.2f - %.2fi\n",real,imag,real,imag);
        }
    }
}

#include<stdio.h>
double fun(int n);

int main(){
    int n;
    double s;
    
    printf("Enter n(1~10): ");
    while(scanf("%d", &n) != EOF) {
        s = fun(n);
        printf("n = %d, s= %f\n\n",n, s);
        printf("Enter n(1~10): ");
    }
    
    return 0;
}

double fun(int n){
double s=1,x=1;
    int i;
    if(n==1)
    return 1;
    else{
    for(i=1;i<=n;i++){
        x=-x*1/i;
        s=s+x;
        }
    return s;
    
    }


}

#include<stdio.h>
#include<stdlib.h>
int isPrime(int);
int main(){
    int i=0,x,s,sum=0;
    for(x=101;x<=200;x++){
        s=isPrime(x);
        if(s==0){
        printf(" %d",x);
        i++;
        x++;
        sum++;
        if(sum%5==0)
        {
            printf(" \n");
        }
     }
 }
 printf("\n101~200之间有素数%d个\n",i);
 system("pause");
    return 0;
    
    
}

int isPrime (int x)
{
    int n=0,i;
    for(i=2;i<x;i++){
        if(x%i==0)
            n++;
    }return n;
}