C语言 反序打印字符串中的单词

int main()
{
    char *str = "see you later";
    int r = strlen(str);
    char * p = str;
    int a= 0;
    while(*str++!='')
    {
        if(*str == ' ')
        {
            a++;
        }
    }
    str-=(r+1);
    int arr[a];
    int i,j;
    for(i =1,j=0;i<r;i++)
    {
        if(*str ==' ')
        {
            arr[j] = i;
            j++;
        }
        str++;
    }
    str-=(r-1);
    //puts(p+arr[1]);
    char arr2[r+1];
    int k = 0;
    puts(p);
    while(*str!='')
    {
        if(*str == ' ')
        {
            arr2[k] = '';
        }
        else
        {
            arr2[k] = *str;
        }
        str++;
        k++;
    }
    arr2[k] = '';
    p = arr2;
    for(i = a-1;i>=0;i--)
    {
        puts(p+arr[i]);
    }
    puts(p);

    return 0;
}