void calculation(double x1, double x2, char c) //计算器 { switch(c) { case '+': printf("%.4f+%.4f=%.4f\n",x1,x2,x1+x2); break; case '-': printf("%.4f-%.4f=%.4f\n",x1,x2,x1-x2); break; case '*': printf("%.4f*%.4f=%.4f\n",x1,x2,x1*x2); break; case '/': if(x2) { printf("%.4f/%.4f=%.4f\n",x1,x2,x1/x2); } e...