一、运行结果；

二、源代码；

# define _CRT_SECURE_NO_WARNINGS
# include <stdio.h>
# include <math.h>//声明函数；
//判断条件等于0时；
void zeor(double a, double b);//判断条件大于0时；
void bigzeor(double p, double q);//判断条件小于0时；
void smallzeor();int main()
{//初始化变量值；double a, b, c, p, q, judge;//获取用户输入数据；printf("请输入a, b, c的值:");scanf("%lf %lf %lf", &a, &b, &c);//运算；judge = b * b - 4 * a * c;p = -b / (2.0 * a);q = sqrt(judge) / (2.0 * a);//判断；if (judge >= 0){if (judge = 0){//调用函数；zeor(a, b);}else{//调用函数；bigzeor(p, q);}}else{//调用函数；smallzeor();}return 0;
}//实现zeor函数；
void zeor(double a, double b)
{//初始换变量值；double x1 = 0;double x2 = 0;//运算；x1 = x2 = (-2.0 * a) / b;//输出结果；printf("函数的根为：x1=x2=%.2f\n", x1);}//实现bigzeor函数；
void bigzeor(double p, double q)
{//初始换变量值；double x1 = 0;double x2 = 0;//运算；x1 = p + q;x2 = p - q;//输出结果；printf("函数的根为：x1=%.2f, x2=%.2f\n", x1, x2);}//实现smallzeor函数；
void smallzeor()
{//输出结果；printf("函数无根!\n");}