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[Tips] What are the keywords __in and __in_opt in C?

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Posted on 10/28/2016 10:28:17 AM | | |

_in Enter the parameters
_out Output parameters
_opt The parameter is optional, i.e. it can be NULL
_ecount The element of the cache to which it points is the number in parentheses
These macros are defined as empty and just make the program easier to understand!
https://msdn.microsoft.com/en-us/library/aa383701(v=vs.85).aspx

Let's take a look at an example:



How do we translate???

[DllImport("user32.dll", EntryPoint = "GetWindowText")]
public static extern int GetWindowText(IntPtr hWnd,String lpString,int nMaxCount)





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