C程序，段异常，谁帮小弟我改改，多谢

C程序，段错误，哪位高手帮我改改，谢谢。

C/C++ code

错误出现在这一句：ST->elem = (ElemType*)malloc(sizeof(ElemType)); #include <stdio.h>#define ERROR -1#define SUCCEED 0//#define EQ(a,b)   (!strcmp((a),(b)))typedef int KeyType;typedef struct{    char stu_id[15];    char name[20];    char Chinese[5];    char math[5];    char English[5];}ElemType;typedef struct{    ElemType *elem;    int length;}SSTable;int Create(SSTable *ST, int n){    ST->elem = (ElemType*)malloc(sizeof(ElemType)); //错误点    if (NULL == ST->elem)    {        return ERROR;    }    else    {        return SUCCEED;    }    return 0;}int main(void){    SSTable *ST;    Create(ST,5);    //printf("%s",ST->elem->stu_id);    printf("HELLO\n");    return 0;}