The simple fopen operation seems to not work. perror returns - Invalid argument. What could be wrong.

I have a ascii file called abc.dat in R:.

```
int main()
{
    FILE *f = fopen("R:\abc.dat","r");
    if(!f)
    {
        perror ("The following error occurred");

        return 1;
    }
}

```

Output:

> 
> The following error occurred: Invalid argument.
> 
> 
>