数据结构非递归二分查找法

#include<stdio.h>
#include<stdlib.h>

typedef int KeyType;

typedef struct{
    KeyType key;
}ElemType;

typedef struct{

    ElemType *elem;
    int length;
}SSTable;

enum status{
    error,ok
};

status EQ(KeyType key,KeyType y)
{
    if(key==y)
        return ok;
    else
        return error;
}

status LT(KeyType key,KeyType y)
{
    if(key<y)
        return ok;
    else
        return error;
}

int searchBin(SSTable ST,KeyType key)
{


    int low=1;
    int high=ST.length;
    while(low<=high)
    {
        int mid=(low+high)/2;
        if(key==ST.elem[mid].key)
            return mid;
        else
            if(key<ST.elem[mid].key)
                high=mid-1;
            else
                low=mid+1;
    }
    return 0;
}
void main()
{
    SSTable ST;
    ST.elem[0].key=5;
    ST.elem[1].key=13;
    ST.elem[2].key=19;
    ST.elem[3].key=21;
    ST.elem[4].key=37;
    ST.elem[5].key=56;
    ST.elem[6].key=64;
    ST.elem[7].key=75;
    ST.elem[8].key=80;
    ST.elem[9].key=88;
    ST.elem[10].key=92;   
    int m=searchBin(ST,13);
    printf("m=%d",m);
}




这个程序运行时出现异常，亲能帮我解决一下吗？出现一个警告是ST未被初始化