#include<stdio.h>   //请帮我看看，这程序哪里有问题。。才导致下面的运行结果。这是求ax^2+bx+c=0的根的程序

#include<math.h>
    void fun1(double a,double b,double c,double d)      //Δ=0的情况
    {
        double ans=-b/(2*a);
        printf("b^2-4*a*c==0,x1=x2=%lf.\n",ans);
        }
 void fun2(double a,double b,double c,double d)  //Δ>0的情况
 {
     double ans1,ans2;
     ans1=(-b-sqrt(d))/(2*a);
     ans2=(-b-sqrt(d))/(2*a);
     printf("b^2-4*a*c>0,x1=%lf,x2=%lf.\n",ans1,ans2);
 }，
 void fun3(double a,double b,double c,double d)  //Δ<0的情况，输出复数解
 {
     double real,imar;
     real=-b/(2*a);
     imar=sqrt(-d)/(2*a);
     printf("b*b-4*a*c<0,x1=%lf+%lfi,x2=%lf-%lfi.\n",real,imar,real,imar);
 }
 int main(）      //我感觉是不是主函数的问题
 {
     void fun1(double a,double b,double c,double d);
     void fun2(double a,double b,double c,double d);
     void fun3(double a,double b,double c,double d);
     double a,b,c,d;
     printf("please intput a,b,c.\n");
     while(scanf("%lf，%lf，%lf",&a,&b,&c)!=EOF)      
        {
         d=b*b-4*a*c;
         if(d==0)fun1(a,b,c,d);
         else if(d>0)fun2(a,b,c,d);
         else fun3(a,b,c,d);
         printf("please enter put a,b,,c.\n");
     }
}

           //无限循环，用的DEV编译器

[此贴子已经被作者于2016-5-25 16:24编辑过]

你确定你的程序能运行吗？
void fun2(double a,double b,double c,double d)  //Δ>0的情况
 {
     double ans1,ans2;
     ans1=(-b-sqrt(d))/(2*a);
     ans2=(-b-sqrt(d))/(2*a);
     printf("b^2-4*a*c>0,x1=%lf,x2=%lf.\n",ans1,ans2);
 }，  //这里多个逗号什么鬼

int main(）  //这个括号右半边是中文输入法下的括号吧？
至于你说的无限循环的问题，应该while这句的问题，你查下scanf返回值的相关内容看看

[此贴子已经被作者于2016-5-25 16:57编辑过]

能运行啊，我都发图了。

#include<stdio.h>  

#include<math.h>
    void fun1(double a,double b,double c,double d)   
    {
        double ans=-b/(2*a);
        printf("b^2-4*a*c==0,x1=x2=%lf.\n",ans);
        }
 void fun2(double a,double b,double c,double d)  
 {
     double ans1,ans2;
     ans1=(-b-sqrt(d))/(2*a);
     ans2=(-b+sqrt(d))/(2*a);
     printf("b^2-4*a*c>0,x1=%lf,x2=%lf.\n",ans1,ans2);
 }
void fun3(double a,double b,double c,double d)
 {
     double real,imar;
     real=-b/(2*a);
     imar=sqrt(-d)/(2*a);
     printf("b*b-4*a*c<0,x1=%lf+%lfi,x2=%lf-%lfi.\n",real,imar,real,imar);
 }


 int main()      
 {
     void fun1(double a,double b,double c,double d);
     void fun2(double a,double b,double c,double d);
  
     double a,b,c,d;
     printf("please intput a,b,c.\n");
     scanf("%lf,%lf,%lf",&a,&b,&c);     
        
         d=b*b-4*a*c;
         if(d==0)fun1(a,b,c,d);
         if(d>0)fun2(a,b,c,d);
         if(d<0)fun3(a,b,c,d);
        
         printf("please enter put a,b,c.\n");
         return 0;
     
}
我给你改了一下 现在应该好了

那就看下你的帖子上程序是不是你手写时候出错了，多个逗号，括号一半是中文输入法的。

确实好了。但是我希望可以循环输入的。用while语句怎么不行？