yiyuan.cpp

用C++写的求解一元二次方程的源程序

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


void main()  
{ double a,b,c,s,x1,x2,t;  
        cout<<"Please enter a,b,c\n";  
cin>>a>>b>>c;  
cout<<"输入方程是:\n";  
cout<<a<<"*(X*X)"<<"+"<<b<<"*X"<<"+"<<c<<"="<<"0"<<endl;  
cout<<'\n';  
        s=b*b-4*a*c;  
t=sqrt(fabs(s));  
cout<<s<<endl;  
if(s=0)  
{  
  cout<<"There is only one x\n";   
  x1=x2=(-b)/(2*a);  
}  
else if(s>0)  
{   
 cout<<"There are two x\n";  
 x1=(-b+t)/(2*a);  
 x2=(-b-t)/(2*a);  
}  
     else if(s<0)  
 {  
  cout<<"There is no such x\n";  
 }  
}