Windows API Reference

Base API Reference

This section provides documentation for fundamental Windows API functions and structures that are essential for most Windows applications. These APIs cover core functionalities such as memory management, process and thread management, handles, and error handling.

HeapAlloc

Allocates a block of memory from a specified heap.

LPVOID HeapAlloc(
  HANDLE hHeap,
  DWORD  dwFlags,
  SIZE_T dwBytes
);
                

Parameters

Return Value

If the function succeeds, the return value is a pointer to the allocated memory block. If the function fails, the return value is NULL. To get extended error information, call GetLastError.

HeapFree

Frees a block of memory previously allocated from a specified heap by the HeapAlloc or HeapReAlloc function.

BOOL HeapFree(
  HANDLE hHeap,
  DWORD  dwFlags,
  LPVOID lpMem
);
                

Parameters

Return Value

If the function succeeds, the return value is TRUE. If the function fails, the return value is FALSE. To get extended error information, call GetLastError.

GetLastError

Retrieves the last error value set by a failed function call.

DWORD GetLastError(void);
                

Return Value

The return value is the last error code set by the calling thread. A return value of 0 is not a valid error code.

SetLastError

Sets the last-error code for the calling thread.

VOID SetLastError(
  DWORD dwErrCode
);
                

Parameters

Remarks

Use this function to set the last-error code for a thread before returning from a function that fails. Most system services set the last-error code when they fail.

GetCurrentProcess

Retrieves a pseudo handle for the current process.

HANDLE GetCurrentProcess(void);
                

Return Value

The return value is a pseudo handle to the current process. This handle is unique to the calling process and has the maximum possible access rights over the process. This pseudo handle can be used only by the current process; it cannot be inherited by child processes or used in functions that require an open handle to a process.

GetCurrentThread

Retrieves a pseudo handle for the current thread.

HANDLE GetCurrentThread(void);
                

Return Value

The return value is a pseudo handle for the current thread. This handle is unique to the calling thread and has the maximum possible access rights over the thread. This pseudo handle can be used only by the current thread; it cannot be inherited by child threads or used in functions that require an open handle to a thread.

CreateProcess

Creates a new process and its primary thread in the calling process's address space.

BOOL CreateProcess(
  LPCSTR                lpApplicationName,
  LPSTR                 lpCommandLine,
  LPSECURITY_ATTRIBUTES lpProcessAttributes,
  LPSECURITY_ATTRIBUTES lpThreadAttributes,
  BOOL                  bInheritHandles,
  DWORD                 dwCreationFlags,
  LPVOID                lpEnvironment,
  LPCSTR                lpCurrentDirectory,
  STARTUPINFOA          *lpStartupInfo,
  PROCESS_INFORMATION   *lpProcessInformation
);
                

Remarks

CreateProcess provides access to the command-line string used to create the process, environment variables, and the working directory. It also provides more control over priority class and optimizations.

ExitProcess

Terminates the calling process and all of its threads.

VOID ExitProcess(
  UINT uExitCode
);
                

Parameters

Remarks

The system does not close the process handle of the calling process until the last thread of the process has terminated. Therefore, you can call ExitProcess from any thread in the process. The exit code can be used to retrieve process status information using the GetExitCodeProcess function.