C++的代碼：
#include <iostream.h>
#include <math.h>
void main(void)
{
double a,b,c,d;
char ch('y');
do{
cout<<"請依次輸入二次方程ax^2+bx+c=0的系數(shù)(a不等于0):"<<endl;
cin>>a>>b>>c;
if(-0.0001<a<0.0001) //浮點數(shù)不宜直接判斷相等
d=b*b-4*a*c;
if(d==0)cout<<"方程有兩個相等實根："<<-b/(2*a)<<endl;
else if(d<0)cout<<"方程有兩個不相等復(fù)根:"<<-b/(2*a)<<"+i"<<sqrt(-d)/(2*a)<<' '<<-b/(2*a)<<"-i"<<sqrt(-d)/(2*a)<<endl;
else cout<<"方程有兩個不相等實根:"<<-b/(2*a)+sqrt(d)/(2*a)<<' '<<-b/(2*a)+sqrt(d)/(2*a)<<endl;
cout<<"繼續(xù)?(y/n):";cin>>ch;
}while(ch=='y'||ch=='Y');
}