求解一元二次方程

/*
求解一元二次方程
*/
#include <stdio.h>
#include <string.h>
#include <math.h>

int  solveEquation(const double a,const double b,const double c)
{
double x1,x2;
double delta = b*b - 4*a*c;
if(a == 0){
printf("a = 0 is not quadratic equation with one unknown!\n");
return 0;
}
if(delta > 0){
//两个解
x1 = (-b + sqrt(delta)) / (2*a);
x2 = (-b - sqrt(delta)) / (2*a);
printf("两个解:\nx1 =\t%lf\nx2 =\t%lf\n",x1,x2);
}else if(delta == 0){
//唯一解
x1 = (-b) / (2*a);
printf("唯一解:x1 = x2 = %lf\n",x1);
}else{
//无解
printf("无解！\n");
}
}

int main(int argc, char* argv[])
{
double a, b, c;
int key = 0,count = 1;;
a = b = c = 0;

while(count)
{
printf("Please input a, b, c and a != 0:");
scanf("%lf%lf%lf",&a,&b,&c);
solveEquation(a,b,c);

//继续或者循环控制
printf("continue intput (y or n)?\n");
key = getch();
if (key == 'n' || key == 'N'){
count = 0;
}
}
return 0;
}