diff.md

public static void CopyFile(string from, string into) 
{
    using (var fromFile = File.Open(from, FileMode.Open, FileAccess.Read))
    using (var toFile = File.Open(into, FileMode.Create, FileAccess.Write))
    {
    // ... Perform actual file copy

    // Both FileStream objects are disposed at the end of the enclosing scope, 
    // in this case, the method declaration.
    }
}

public static void CopyFile(string from, string into) 
{
    using scoped var fromFile = File.Open(from, FileMode.Open, FileAccess.Read);
    using scoped var toFile = File.Open(into, FileMode.Create, FileAccess.Write);
    // ... Perform actual file copy

    // Both FileStream objects are disposed at the end of the enclosing scope, 
    // in this case, the method declaration.
}