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#include<stdio.h>
#include<math.h>
 void main()
  {
  	float a,b,c,disc,x1,x2,realpart,imagpart;
  	scanf ("%f,%f,%f",&a,&b,&c);
  	printf("The equation" );
  	if(fabs(a)<=1e-6)
  	   printf("is not a quadratic\n");
  	else 
  	   {
  	       disc=b*b-4*a*c;
  	       if(fabs(disc)<=1e-6)
  	          printf("has two equal roots:%8.4f\n",-b/(2*a));
  	       else
  	          if(disc>1e-6)
  	       {
  	     	x1=(-b+ sqrt(disc))/(2*a);
  	     	x2=(-b-sqrt(disc))/(2*a);
  	     	printf("has distinct real roots:%8.4f and%8.4f\n",x1,x2);
  	       }
  	       else
  	       {
  	     	realpart=-b/(2*a);
  	     	imagpart=sqrt(-disc)/(2*a);
  	     	printf("has complex roots:\n");
  	     	printf("%8.4f+%8.4fi\n",realpart,imagpart);
  	     	printf("%8.4f-%8.4fi\n",realpart,imagpart);
  	     	
  	       }
  	 	
  	   }
  	printf("2013304137");
  	}

     编写程序时，必须先对几种情况的结果进行分析；其次，还要注意for、else函数的应用。