be carefull in c

#include <stdio.h>

int arr[]={0,1,2,3,4};
#define TOTAL_ELEMENTS (sizeof(arr)/sizeof(arr[0]))

int main(int argc,char *argv[])
{
    int d=-1,x;
    if(d <= (int)TOTAL_ELEMENTS-1)
    //这里如果是if(d <= TOTAL_ELEMENTS-1)的话，下面的语句不会执行
    //because  TOTAL_ELEMENT is unsigned int
    //so  d is change to unsigned, while d=-1 it change to oxFFFFFFFF
    //so when compare tow numbers be careful it's type changing
    {
        x = arr[d+1];
    }
    printf("%d",x);
}