error: initializer element is not constant 错误
typedef struct student {
  char name[20]
  char phone[20];
  bool flag;
  struct student *next;
}stu;

stu *Read(stu * phead);
struct student *head = NULL;

head = Read(head);


phonetext.c:22: warning: data definition has no type or storage class
phonetext.c:22: error: conflicting types for ‘head’
phonetext.c:20: note: previous definition of ‘head’ was here
phonetext.c:22: warning: passing argument 1 of ‘Read’ makes pointer from integer without a cast
phonetext.c:14: note: expected ‘struct stu *’ but argument is of type ‘int’
phonetext.c:22: warning: initialization makes integer from pointer without a cast
phonetext.c:22: error: initializer element is not constant
phonetext.c: In function ‘Schedle’:


不知道怎么解决，谢谢帮忙。

------解决方案--------------------
用c99标准，试试加-std=c99