实验三

#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 = 1+rand() %30;  
        printf("%3d", x);
    }
    
    printf("\n");
    
    return 0;
} 

#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("%lf%lf%lf", &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>
#include<stdlib.h>
#include<time.h>
#define  N 1
int main(){
	int x,n,y;
	unsigned char i;
	
	      printf("猜一猜2021年5月哪一天会是你的luck day\n");
	
	     printf("开始咯，你有三次机会，猜吧（1~31）：\n");
	     	for(i=0;i<3;i++){
	     scanf("%d",&y);
	     srand(time(0));
	     for(n=1;n<=N;n++){
	 	 x=1+rand()%30;
		 if(y==x)
		 printf("是的那就是你的幸运日\n");

		else if(x<y) {
		 printf("你猜的日期晚了，luck day悄悄溜到前面去了\n");
		 printf("再猜（1~31）：\n");}
		 else if(x>y){
			printf("你猜的日期早了，luck day溜到后面去了\n");
			printf("再猜（1~31）：\n");
		}
	}
	
      } 
	  printf("次数用完了。偷偷告诉你：5月你的luck day是 %d号",x);
	  return 0;
} 

　

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

#include <stdio.h>
double fun(int n);  // 函数声明 
 
int main() {
    int n;
    double s;
    
    printf("Enter n(1~10): ");
    while(scanf("%d", &n) != EOF) {
        s = fun(n);  // 函数调用 
        printf("n = %d, s= %f\n\n", n, s);
        printf("Enter n(1~10): ");
    }
    
    return 0;
}


double fun(int n)
 {
     double result;
     if (n==1)
    result = 1;
   else if (n==2)
   result=0.5;
   else
   result=(-1)*fun(n-1)*1/n+fun(n-2)*1/n+fun(n-1);
   return result;
}

 

#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("%lf%lf%lf", &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);  // 函数声明 
 
int main() {
    int n;
    double s;
    
    printf("Enter n(1~10): ");
    while(scanf("%d", &n) != EOF) {
        s = fun(n);  // 函数调用 
        printf("n = %d, s= %f\n\n", n, s);
        printf("Enter n(1~10): ");
    }
    
    return 0;
}


double fun(int n)
 {
     double result;
     if (n==1)
    result = 1;
   else if (n==2)
   result=0.5;
   else
   result=(-1)*fun(n-1)*1/n+fun(n-2)*1/n+fun(n-1);
   return result;
}

#include<stdio.h>
#include<math.h> 
int isprime(int n);
      int main()
     {
        int i,x=0,m=1;
        for(i=101;i<200;i++)
        {
            if(isprime(i)!=0)
             {
            printf("%d ",i);
             x++;
             m++;
            }
            while(m>5)
            {
            printf("\n");
            m=1;
             }
         }
         printf("\n");
           printf("一共有: %d个素数\n ",x);
           return 0;
    } 
int isprime(int n)
{
     int k;
     for(k=2;k<=sqrt(n);k++)
     if(n % k == 0)
       return 0;
       return 1;
}