GetProcessId

Retrieves the process identifier of the specified process.

Header

#include <processthreadsapi.h>

Syntax

DWORD GetProcessId(
    HANDLE hProcess
);

Parameters

Parameter	Description
`hProcess`	Handle to the process. The handle must have the PROCESS_QUERY_INFORMATION or PROCESS_QUERY_LIMITED_INFORMATION access right.

Return value

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

Remarks

The process identifier is unique system‑wide for the lifetime of the process.
Do not close the handle before calling GetProcessId.
Available on Windows Vista and later.

Example

C++

#include <windows.h>
#include <iostream>

int main() {
    STARTUPINFO si = { sizeof(si) };
    PROCESS_INFORMATION pi;
    if (CreateProcess(L"C:\\Windows\\System32\\notepad.exe",
                      NULL, NULL, NULL, FALSE, 0, NULL, NULL,
                      &si, &pi)) {
        DWORD pid = GetProcessId(pi.hProcess);
        std::wcout << L"Process ID: " << pid << std::endl;
        CloseHandle(pi.hThread);
        CloseHandle(pi.hProcess);
    } else {
        std::cerr << "CreateProcess failed: " << GetLastError() << std::endl;
    }
    return 0;
}

using System;
using System.Diagnostics;

class Program {
    static void Main() {
        Process p = Process.Start(@"C:\Windows\System32\notepad.exe");
        Console.WriteLine($"Process ID: {p.Id}");
        p.WaitForExit();
    }
}

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