有一段程序，请大虾指正：
     struct person{
         char name[20];
         int age;
         char sex;
};
void main()
{
     struct person a={"Liming",23,'m'};
     struct person b;
     b=a;
      b.age=21;
      b.sex='f' ;
      printf("%s is a man.\n",b.name);
}
编译时提示：error c2065::"printf":undeclared identifier.

#include<stdio.h>

谢谢。