#include <stdlib.h>
#include <stdio.h>
#include <string.h>

main(argc,argv)
int argc;
char **argv;
{ double v1,v2,op ;
  int oper ;


  if (argc < 4)
  {printf("calc operand1 (+,-,*,/) operand2\n");return(0);}

  if (sscanf(argv[1],"%lf",&v1) <= 0)
  {printf("Error, first field must be a number\n");return(0);}

  if      (strcmp(argv[2],"+")==0) oper=0 ;
  else if (strcmp(argv[2],"-")==0) oper=1 ;
  else if (strcmp(argv[2],"*")==0) oper=2 ;
  else if (strcmp(argv[2],"/")==0) oper=3 ;
  else
  {printf("Error, second field must be +,-,*,/\n");return(0);}

  if (sscanf(argv[3],"%lf",&v2) <= 0)
  {printf("Error, third field must be a number\n");return(0);}

  if ((oper==3) && (v2==(double)(0)))
  {printf("Error, division by zero\n");return(0);}


  if       (oper==0) op=v1+v2 ;
  else if  (oper==1) op=v1-v2 ;
  else if  (oper==2) op=v1*v2 ;
  else               op=v1/v2 ;

  printf("%lf %s %lf = %lf\n",v1,argv[2],v2,op);

  return(0);

}