you write the following code segment to call a function from win32..., Basic,

Question:You write the following code segment to call a function from the Win32 Application Programming Interface (API) by using platform invoke.
string personName = "N?el";
string msg = "Welcome " + personName + " to club ''!";
bool rc = User32API.MessageBox(0, msg, personName, 0);
You need to define a method prototype that can best marshal the string data.
Which code segment should you use?

A [DllImport("user32", CharSet = CharSet.Ansi)] 
public static extern bool MessageBox(int hWnd, 
String text, 
String caption, 
uint type);} 
B [DllImport("user32", CharSet = CharSet.Unicode)] 
public static extern bool MessageBox(int hWnd 
String text,
 String caption, 
uint type);
} 
C [DllImport("user32", EntryPoint = "MessageBoxA", 
CharSet = CharSet.Ansi)] 
public static extern bool MessageBox(int hWnd, 
[MarshalAs(UnmanagedType.LPWStr)]String text,
 [MarshalAs(UnmanagedType.LPWStr)]String caption, 
uint type);} 
D [DllImport("user32", EntryPoint = "MessageBoxA", 
CharSet = CharSet.Unicode)] 
public static extern bool MessageBox(int hWnd, 
[MarshalAs(UnmanagedType.LPWStr)]String text, 
[MarshalAs(UnmanagedType.LPWStr)]String caption, 
uint type); 
}

/447

+ AnswerB

+ Report

Descriptive on Basic Ebook

Total Preview: 1229

A [DllImport("user32", CharSet = CharSet.Ansi)] public static extern bool MessageBox(int hWnd, String text, String caption, uint type);}

B [DllImport("user32", CharSet = CharSet.Unicode)] public static extern bool MessageBox(int hWnd String text, String caption, uint type);}

C [DllImport("user32", EntryPoint = "MessageBoxA", CharSet = CharSet.Ansi)] public static extern bool MessageBox(int hWnd, [MarshalAs(UnmanagedType.LPWStr)]String text, [MarshalAs(UnmanagedType.LPWStr)]String caption, uint type);}

D [DllImport("user32", EntryPoint = "MessageBoxA", CharSet = CharSet.Unicode)] public static extern bool MessageBox(int hWnd, [MarshalAs(UnmanagedType.LPWStr)]String text, [MarshalAs(UnmanagedType.LPWStr)]String caption, uint type); }

B

A [DllImport("user32", CharSet = CharSet.Ansi)]
public static extern bool MessageBox(int hWnd,
String text,
String caption,
uint type);}

B [DllImport("user32", CharSet = CharSet.Unicode)]
public static extern bool MessageBox(int hWnd
String text,
String caption,
uint type);
}

C [DllImport("user32", EntryPoint = "MessageBoxA",
CharSet = CharSet.Ansi)]
public static extern bool MessageBox(int hWnd,
[MarshalAs(UnmanagedType.LPWStr)]String text,
[MarshalAs(UnmanagedType.LPWStr)]String caption,
uint type);}

D [DllImport("user32", EntryPoint = "MessageBoxA",
CharSet = CharSet.Unicode)]
public static extern bool MessageBox(int hWnd,
[MarshalAs(UnmanagedType.LPWStr)]String text,
[MarshalAs(UnmanagedType.LPWStr)]String caption,
uint type);
}