【问题】用C++结构体实现顺序表，数据超过数组长度后，表长自动+1

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

#define LIST_INIT_SIZE 100
#define LISTINCREMENT 10

typedef int ElemType;

typedef struct
{
    ElemType elem[LIST_INIT_SIZE];
    int length;
    int listsize;
}SqList;

class Sq
{
    public:
        SqList sqList;

        Sq();
        ElemType getElem(int i);
        bool listInsert(int i, ElemType e);
        bool listDelete(int i, ElemType &e);
};

Sq::Sq()
{
    this->sqList.length = 0;
    this->sqList.listsize = LIST_INIT_SIZE;
}

ElemType Sq::getElem(int i)
{
    if (i<1 || i>sqList.length) return ElemType();

    ElemType elem = sqList.elem[i - 1];

    return elem;
}

bool Sq::listInsert(int i, ElemType e)
{
    if (i<1 || i>sqList.length + 1) return false;

    for (int j = sqList.length - 1; j >= i; j++)
    {
        sqList.elem[j + 1] = sqList.elem[j];
    }

    if(i==101)
    {
        printf("%d
",sqList.length);//100
    }
    sqList.elem[i - 1] = e;
    if(i==101)
    {
        printf("%d
",sqList.length);//101
    }
    ++sqList.length;
    if(i==101)
    {
        printf("%d
",sqList.length);//102
    }
    return true;
}

int main()
{
    Sq sq;
    for (int i = 1; i <= 102; i++)
    {
        sq.listInsert(i, i);
    }
    
    return 0;
}

当i==10时，sq.listInsert(int,int)方法中，插入之后length自动+1？？？执行自动操作后又自动+1。