int a1,b1,a2,b2;
sscanf(num1,"%d+%di",&a1,&b1);
	sscanf(num2,"%d+%di",&a2,&b2);
string s;
sscanf(s.c_str(), "%d:%d", );
   //读取实部和虚部  

   char* ans=(char*)malloc(sizeof(char)*13);
   sprintf(ans,"%d+%di",a1*a2-b1*b2,a1*b2+a2*b1);