实验3

实验任务1

#include <math.h>
#include <stdio.h>
int main() 
{
    float a, b, c, x1, x2;
    float delta, real, imag;
    printf("Enter a, b, c: ");
    while(scanf("%f%f%f", &a, &b, &c) != EOF) 
    {
        if(a == 0)
        printf("not quadratic equation.\n\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\n", x1, x2);
            } 
            else 
            {
                real = -b/(2*a);
                imag = sqrt(-delta) / (2*a);
                printf("x1 = %.2f + %.2fi, x2 = %.2f - %.2fi\n\n", real,imag, real, imag);
            }
        }
        printf("Enter a, b, c: ");
    }
    return 0;
    }
 

 

实验任务2

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 5
int main() 
{
    int x, n;
    srand(time(0)); 
    n = 0;
    do 
    {
       n++;
       x = rand()%10; 
       printf("%3d", x);
    }
    while(n<N);
    printf("\n");
    return 0;
}

 

实验任务3

#include<stdio.h>
#include<math.h>
int main()
{
    int x,n,i,k=0,a=0;
    for(x=101;x<=200;x++)
       {
           for(i=2;i<=sqrt(x);i++)
           {
               if(x%i==0)
               break;
               }
               if(i>sqrt(x))
               {
               printf("%4d",x);
                  k++;
                  n++;
                  if(n%5==0)
                  printf("\n");
               }
           }
    
    printf("\n101~200之间共有%d个素数\n",k);
    
    return 0;
} 

 

试验任务4

#include<stdio.h>
#include<math.h>
int main ()
{
    long  x;
    int s,a,k;
    printf("Enter a number:");
    while(scanf("%ld",&x)!=EOF)
    {
        s=0;k=0;
        while(x!=0)
        {
            a=x%10;
            if(a%2!=0)
            {
            s=pow(10,k)*a+s;
            k++;
            }
            x=x/10;
        }
        printf("new number is:%d",s);
        printf("\nEnter a number:");
    }
    
    
    return 0;
}

 

试验任务5

#include<stdio.h>
#include<math.h>
int main()
{
    int n,i,a;
    float t;    
    printf("Enter n(1~10):");
    while(scanf("%d",&n)!=EOF)
    {
        float s=0;
        int m=1;
        a=-1;
        for(i=1;i<=n;i++)
        {
            m=m*i;
            a=a*(-1);
            t=a*1.0/m;
            s=s+t;
            
        }
        printf("n=%d,s=%f\n",n,s);
        printf("\nEnter n(1~10):");
    }
    return 0;
}

 

实验任务6

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

int main(){
    int x,date,i,a=0;
    srand(time(0));
    date=rand()%31;
    printf("猜猜2020年12月哪一天会是你的lucky day\n开始喽，你有三次机会，猜吧（1~3）："); 
    for(i=1;i<=3;i++){
        scanf("%d",&x);
        if(x>date)printf("\n你猜的日期晚了，lucky day悄悄溜到前面啦");
        else if(x<date) printf("\n你猜的日期早了，lucky day还没到呢");
        else {
            a=1;
            printf("\n你猜中了！");
            break;
        };
         
        if(i!=3)printf("\n再猜（1~31）： "); 
        
    }
    if(a==0)printf("\n\n次数用完啦。偷偷告诉你：12月，你的lucky day是%d号",date);
    
    return 0;
    
}