About Calling Windows API functions in C # [Introduction]

Reference

Calling Windows API functions in C # [Reference]

 

For Windows system API function calls inProgramSometimes it is essential in design.Programming LanguageThe calling methods and interfaces are both standardized. The Calling methods in C # language are as follows (the following programming environment is Visual Studio. NET ):

1. Add a new class item to the project, open the class file, and add a reference to the following namespace in the file header:

Using system. runtime. interopservices;

In the class definition subject, the reference to the API is added to the static call method. The following API call is used as an example:

/// <Summary>

/// Open and close the CD tray.

/// </Summary>

[Dllimport ("winmm. dll", entrypoint = "mcisendstring", charset = charset. Auto)]

Public static extern int mcisendstring (string lpstrcommand, string lpstrreturnstring, int ureturnlength, int hwndcallback );

/// <Summary>

/// Display and hide the mouse pointer.

/// </Summary>

[Dllimport ("user32.dll", entrypoint = "showcursor", charset = charset. Auto)]

Public static extern int showcursor (INT bshow );

 

/// <Summary>

/// Clear the recycle bin.

/// </Summary>

[Dllimport ("shell32.dll", entrypoint = "shemptyrecyclebin", charset = charset. Auto)]

Public static extern long shemptyrecyclebin (intptr hwnd, string pszrotpath, long dwflags );

 

/// <Summary>

/// Open the browser

/// </Summary>

[Dllimport ("shell32.dll", entrypoint = "ShellExecute", charset = charset. Auto)]

Public static extern int ShellExecute (intptr hwnd, string lpoperation, string lpfile, string lpparameters, string lpdirectory, int nshowcmd );

 

/// <Summary>

/// Maximize the window, minimize the window, normal size window;

/// </Summary>

[Dllimport ("user32.dll", entrypoint = "showwindow", charset = charset. Auto)]

Public static extern int showwindow (intptr hwnd, int ncmdshow );

 

 

2. With the above file, you can call the above API in the event processing of your own form object. The method is as follows:

The following strreturn is a public variable of the string type. apicils refers to the class name created in the first step.

Open the CD tray:

Long lngreturn = apicils. mcisendstring ("set cdaudio door open", strreturn, 127, 0 );

Close the CD tray:

Long lngreturn = apicils. mcisendstring ("set cdaudio door closed", strreturn, 127, 0 );

Show the mouse pointer in the application form:

Apicwalls. showcursor (1 );

Hide the mouse pointer in the application form:

Apicwalls. showcursor (0 );

Clear the recycle bin:

Apicils. shemptyrecyclebin (Form. activeform. Handle, "", 0x00000000 );

Open the browser window. textbox1.text indicates the URL to be accessed:

Long lngreturn = apicils. ShellExecute (Form. activeform. Handle, "open", textbox1.text, "", "", 1 );

Maximum window:

Apicwalls. showwindow (Form. activeform. Handle, 3 );

Minimize window:

Apicwalls. showwindow (Form. activeform. Handle, 2 );

Restore normal size window:

Apicwalls. showwindow (Form. activeform. Handle, 1 );