c语言结构体指针问题

Question

#include<stdio.h>
#include<stdlib.h>
#define OK 2
typedef int Status; 
typedef int ElemType;
typedef struct{
    ElemType *elem;
    int length;
}SqList; 
Status ListInsert(SqList *L,int e){
    
    ElemType *q=(L->elem);
    ElemType *p=L->elem+L->length-1;
    for(p;p>=q;p--){
        if(*p>e){
            *(p+1)=*p;
            *p=e;
        }
        else
            break;
    }
    L->length++;
    return OK;
}
int main(){
    SqList L;
    L.elem=(ElemType *)malloc(100*sizeof(ElemType));
    int a[]={1,3,5,7};
    L.elem=a;
    L.length=4;
    ListInsert(&L,4);
    for(int i=0;i<L.length;i++) printf("%d ",*(L.elem+i));
    return 0;
} 

请问为什么结果打印不出来

Answer 1

供参考：

#include <stdio.h>
#include <stdlib.h>
#define OK 2
typedef int Status;
typedef int ElemType;
typedef struct {
    ElemType* elem;
    int length;
}SqList;
Status ListInsert(SqList* L, int e) {

    ElemType* q = (L->elem);
    ElemType* p = L->elem + L->length - 1;
    for (p; p >= q; p--) {
        if (*p > e) {
            *(p + 1) = *p;
            *p = e;
        }
        else
            break;
    }
    L->length++;
    return OK;
}
int main() {
    int i;
    SqList L;
    L.elem = (ElemType*)malloc(100 * sizeof(ElemType));
    L.length = 0;
    int a[] = { 1,3,5,7 };
    L.length = sizeof(a) / sizeof(a[0]);
    //L.elem = a;
    for (i = 0; i < L.length; i++)
        L.elem[i] = a[i];
    ListInsert(&L, 4);
    for (int i = 0; i < L.length; i++) printf("%d ", *(L.elem + i));
    return 0;
}