int main ( )
{
    double  A,B,C,x1,x2,x;
    printf ("请输入三个数字： ");
    scanf ("%1f %1f %1f",&A,&B,&C);
    if (A==0.0)
       {
          if (B==0.0)
              printf ("Error");
          else
              printf ("x=%f\n",-C/B);
              
       }
    else  if  (B==0.0)
           {
               if (A*C>=0.0)
                   printf ("x1=+j%f,x2=-j%f\n",sqrt(C/A),sqrt(C/A));
               else
                   printf ("x1=+%f,x2=-%f\n",sqrt(-C/A),sqrt(-C/A));
           }         
            else if (B*B-4*A*C>=0.0)
                    printf ("x1=%f,x2=%f\n",(-B-sqrt(B*B-4*A*C))/(2*A),C/(A*x1));        
                 else
                    printf ("x1=%f+j%f,x2=%f-j%f ",-B/(2A),sqrt(B*B-4*A*C)/2A,-B/(2A),sqrt(B*B-4*A*C/2A ));      
              
        
     system ("pause");
     return 0;                 
      
}
该程序目的是解一元二次方程A*x*x+B*X+C=0,但结果却是“ invalid suffix "A" on integer constant ”。不知何意？请求指点，不胜感激

谢谢指点！不过应在-b/(2*a)前加float.

为什么会出现“invalid suffix "A" on integer constant”。我查了一下是“无效的整形常量后缀”之意！谢谢！