[编程入门]自定义函数求一元二次方程-题解（C语言代码）

^{#include<stdio.h>}

^{#include<math.h>}

^{void root(double a,double b,double c)}

^{

^{double x1,x2,dert;}

^{dert=b*b-4*a*c;}

^if(dert>0)

^{

^{x1=(-b+sqrt(dert))/(2*a);}

^{x2=(-b-sqrt(dert))/(2*a);}

^{printf("x1=%.3lf x2=%.3lf\n",x1,x2);}

^}

^{else if(dert==0)}

^{

^x1=-b/(2*a);

^x2=-b/(2*a);

^{printf("x1=%.3lf x2=%.3lf\n",x1,x2);}

^}

^else

^{printf("x1=%.3lf+%.3lfi x2=%.3lf%.3lfi\n",-b/(2*a),sqrt(-dert)/(2*a),-b/(2*a),-sqrt(-dert)/(2*a));}

^}

^{int main()}

^{

^{double a,b,c;}

^{scanf("%lf%lf%lf",&a,&b,&c);}

^root(a,b,c);

^{return 0;}

^}