5-6.cpp

来自「C程序设计（第3版）程序源代码,提供你最丰富的实际代码」· C++ 代码 · 共 27 行

  #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);
		}
}
}