Question

How to open a filename given in Main’s argv[] (say, D:\a.txt) by CreateFile API?

CreateFile( ReadBuffer, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, 
                                FILE_ATTRIBUTE_NORMAL, NULL );

Answer 1

It looks to me that your problem is simply that you are trying to call a function like this

Connect(char *filename)
{
    HANDLE hFile = CreateFile(filename, ...);
    ....
}

and don’t know how to get hold of the first command-line argument. Do it like this:

int main(int argc, char *argv[])
{
    if (argc != 2)
    {
        printf("Incorrect number of arguments supplied\n.")
        return 1;
    }
    Connect(argv[1]);
    .....
    return 0;
}

Note that argv is an array containing argc items where each item is of type char*. So you simply want the item at index 1. The item at index 0 is the process name.