one or more multiply defined symbols found.

one or more multiply defined symbols found.
#include
int main()
{
int age;
printf("Enter age");
scanf("%d",&age);
printf("g=%d",age);
switch(age)
{
case 2:
case 3:printf("Enter Lower classn");break;
case 4:printf("Enter Middle classn");break;
case 5:
case 6:printf("Enter Higher classn");break;
default:printf("Can't enter n");
}
}
就是用VC6.0做个作业时出现的问题.