Vb System Programming In Practice

VB system programming in Practice By Gouri V

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Introduction to API VB

- A Serious windows development

tool What are Windows APIs? Simple VB API Example Static and Dynamic linking What is a DLL?

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API declaration and syntax[Public | Private] Declare Sub|Function name Lib “libname” Alias “aliasname”] [([arglist])] [As type] Ex. Public Declare Function GetTickCount _ Lib "kernel32.dll" () As Long

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Where does system locates a DLL? DLL disadvantages Right choice – A design issue in analysis phase. 3

Some classic fundas to follow using API 

Using the Any keyword

Declare Sub CopyMemory Lib “kernel32” _ Alias “RtlMoveMemory” (lpvDest As Any, _ lpvSource As any, ByVal cbCopy As Long)

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UDTs and API calls Private Declare Sub GlobalMemoryStatus _ Lib "kernel32" (lpBuffer As MEMORYSTATUS)

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Currency Variables Window Handles Boolean Return Values Limitations of VB to use WIN32 API’s 4

Exploring WIN32 API   

Let’s begin to explore… Kernel32.dll, user32.dll, gdi32.dll Kernel32 overview    

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Memory management Multithreading File operations Process control

Kill running Spyware by Process control 

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CreateToolhelp32Snapshot - Takes a snapshot of the processes and the heaps, modules, and threads used by the processes; returns handle to snapshot. Process32First - Retrieves information about the first process encountered in a system snapshot. Process32Next - Retrieves information about the next process recorded in a system snapshot. 5

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Test Previous instance of Appliaction by CreateMutex Public Declare Function CreateMutex _ Lib "kernel32.dll" _ Alias "CreateMutexA" (lpMutexAttributes As Any, _ ByVal bInitialOwner As Boolean, _ ByVal lpName As String) As Long

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Save, save and save your work often!

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User32 Calls and Gdi32 Calls 

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User32.dll is primarily responsible for, but not limited to:  Windows Management  Menus  Controls Win32 Handles Gdi32.dll call are primarily responsible for, but not limited to, graphical manipulations. Windows Messages Subclassing 7

More interesting about windows messages     

Window Procedures Window Classes Queued Messages Message Loops Nonqueued Messages

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Real time system utilities and challenges      

Remove invalid file extensions Find out and remove Spywares on your PC Make your PC junk free Remove missing softwares Delete malicious startup entries Scanning cookies

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? Thanks!! 10