实验三

//一元二次方程的
#include
#include
int main ()
{
    double a,b,c,x1,x2;
    double delat,real,imag;
    while(scanf("%lf %lf %lf",&a,&b,&c)){
        if(a==0)
          printf("illegal\n");
        else{
              delat=b*b-4*a*c;
              
              if(delat>=0){
                  x1=-b+sqrt(delat)/(2*a);
                  x2=-b-sqrt(delat)/(2*a);
                  printf("x1=%lf x2=%lf\n",x1,x2);
                  }
                  
              if(delat<0){
                  real=-b/(2*a);
                  imag=sqrt(-delat)/(2*a);
                  printf("x1=%lf+%lfi x2=%lf-%lfi\n",real,imag,real,imag);
                  } 
              
          }
    printf("ENTER");    
    }
    return 0;
}

 

 

/* 
编程找出5个整数的最大数和最小数 
《C语言程序设计教程学习指导》p122实验内容(3) 
*/ 

#include 
#include 
int main() {
    int number, max, min, n;
    
    n=1;
    printf("输入第%d个数: ", n);
    scanf("%d", &number);
    max = number;
    min = number;
    
    while(n<=4) {
        n++;
        printf("输入第%d个数: ", n);
        scanf("%d", &number);    

        if(number>max)
            max = number;
        else if(number<min)
            min = number;
    }
    
    printf("最大数为: %d\n", max);
    printf("最小数为: %d\n", min);
    
    system("pause");
    
    return 0;
} 

 

 

#include 
#include 
#include 
int main() {
    int n;int x;int y;x=0;int z;
    for(n=101;n<=200;n++)
    {z=0;
    for(y=2;y<=sqrt(n);y++)
        {if( n%y==0)
           {z=1;
             break;
           }
        }
          if(z==0)
          {
          printf("%4d",n);
          ++x;
          if(x%5==0)
          printf("\n");
          }
         
    }
     printf("\n");
    printf("101~200之间共有%d个素数",x) ;
    return 0;
}  

 

 

#include
#include
int main()
{
    long n;
    int s;int x;int y;
    printf("输入一个整数:");
    scanf("%ld", &n);
         s = 0, x = 1;
    while (n)
    {
    y = n % 10;
        if (y % 2 != 0)
        {
            s = s + y * x;
            x = x * 10;
        }
            n = n / 10;
    }
    printf("新的数字是:%ld\n", s);
    return 0;

}

 

 感想就是涉及到嵌套式的题目总感觉脑回路不清晰。

#include
int main()
{
    int a,n,x,m=0,b=1;
    float s=0;
    printf("Enter n and a:");
    scanf("%d%d",&n,&a);
    for(x=1;x<=n;x++ )
    {
        m=m+a*b;
        b*=10;
        s+=(float)x/m;
}
    printf("%f",s);
}