EnumProcesses function

Retrieves the process identifier for each process object in the system.

Syntax


BOOL WINAPI EnumProcesses(
  _Out_  DWORD *pProcessIds,
  _In_   DWORD cb,
  _Out_  DWORD *pBytesReturned
);

Parameters

pProcessIds [out]

A pointer to an array that receives the list of process identifiers.

cb [in]

The size of the pProcessIds array, in bytes.

pBytesReturned [out]

The number of bytes returned in the pProcessIds array.

Return value

If the function succeeds, the return value is nonzero.

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

Remarks

It is a good idea to use a large array, because it is hard to predict how many processes there will be at the time you call EnumProcesses.

To determine how many processes were enumerated, divide the pBytesReturned value by sizeof(DWORD). There is no indication given when the buffer is too small to store all process identifiers. Therefore, if pBytesReturned equals cb, consider retrying the call with a larger array.

To obtain process handles for the processes whose identifiers you have just obtained, call the OpenProcess function.

Starting with Windows 7 and Windows Server 2008 R2, Psapi.h establishes version numbers for the PSAPI functions. The PSAPI version number affects the name used to call the function and the library that a program must load.

If PSAPI_VERSION is 2 or greater, this function is defined as K32EnumProcesses in Psapi.h and exported in Kernel32.lib and Kernel32.dll. If PSAPI_VERSION is 1, this function is defined as EnumProcesses in Psapi.h and exported in Psapi.lib and Psapi.dll as a wrapper that calls K32EnumProcesses.

Programs that must run on earlier versions of Windows as well as Windows 7 and later versions should always call this function as EnumProcesses. To ensure correct resolution of symbols, add Psapi.lib to the TARGETLIBS macro and compile the program with –DPSAPI_VERSION=1. To use run-time dynamic linking, load Psapi.dll.

Examples

For an example, see Enumerating All Processes or Enumerating All Modules for a Process.

Requirements

Minimum supported client

Windows XP [desktop apps only]

Minimum supported server

Windows Server 2003 [desktop apps only]

Header

Psapi.h

Library

Kernel32.lib on Windows 7 and Windows Server 2008 R2;
Psapi.lib (if PSAPI_VERSION=1) on Windows 7 and Windows Server 2008 R2;
Psapi.lib on Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP

DLL

Kernel32.dll on Windows 7 and Windows Server 2008 R2;
Psapi.dll (if PSAPI_VERSION=1) on Windows 7 and Windows Server 2008 R2;
Psapi.dll on Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP

See also

CreateToolhelp32Snapshot
OpenProcess
Process Information
PSAPI Functions

 

 

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