System.out.println("请输入第二个数");
int num1=sc.nextInt();
int sum=0;
switch ( op)
{
case 1:
System.out.println(num+"+"+num1+"="+(num+num1));
sum=num+num1;
break;
case 2:
System.out.println(num+"-"+num1+"="+(num-num1));
sum=num-num1;
break;
case 3:
System.out.println(num+"*"+num1+"="+(num*num1));
sum=num*num1;
break;
case 4:
System.out.println(num+"/"+num1+"="+(num/num1));
sum=num/num1;
break;
}
System.out.println("请选择要进行的操作:1(继续) 2(退出) 3(清空)");
int op1=sc.nextInt();
if(op1<1||op1>3){
System.out.println("你输入有误,请输入1到3的数字");
op1=sc.nextInt();