A version of this page is also available for

Windows Embedded CE 6.0 R3


This function writes memory in a specified process. The entire area to be written to must be accessible, or the operation fails.


BOOL WriteProcessMemory(
  HANDLE hProcess,
  LPVOID lpBaseAddress,
  LPVOID lpBuffer,
  DWORD nSize,
  LPDWORD lpNumberOfBytesWritten


  • hProcess
    [in] Handle returned from the OpenProcess function that provided full access to the process.
  • lpBaseAddress
    [in] Pointer to the base address in the specified process.

    Before data transfer occurs, the system verifies that all data in the base address and memory of the specified size is accessible for write access. If so, the function proceeds; otherwise, the function fails.

  • lpBuffer
    [in] Pointer to the buffer that supplies data to be written into the address space of the specified process.
  • nSize
    [in] Specifies the requested number of bytes to write into the specified process.
  • lpNumberOfBytesWritten
    [out] Pointer to the number of bytes transferred into the specified process.

    This parameter is optional.

    If lpNumberOfBytesWritten is NULL, the parameter is ignored.

Return Value

Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.

The function fails if the requested write operation crosses into an area of the process that is inaccessible.


WriteProcessMemory copies data from the specified buffer in the current process to the address range of the specified process. The process whose address space is being written to is typically, but not necessarily, being debugged.

The entire area to be written to must be accessible. If it is not, the function fails.


Header winbase.h
Library Nk.lib
Windows Embedded CE Windows CE 2.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also


Process and Thread Functions