如何在C#中调用winapi更改窗口图标

[DllImport("user32.dll", SetLastError = true)]
public static extern IntPtr SetClassLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

private const int GCLP_HICON = -14;
private const int ICON_SMALL = 0;
private const int ICON_BIG = 1;

Icon icon = new Icon("path_to_icon_file.ico");

IntPtr hWnd = Process.GetCurrentProcess().MainWindowHandle;

SetClassLongPtr(hWnd, GCLP_HICON + ICON_SMALL, icon.Handle);
SetClassLongPtr(hWnd, GCLP_HICON + ICON_BIG, icon.Handle);

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Drawing;

public class Program
{
    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr SetClassLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

    private const int GCLP_HICON = -14;
    private const int ICON_SMALL = 0;
    private const int ICON_BIG = 1;

    public static void Main()
    {
        Icon icon = new Icon("path_to_icon_file.ico");
        IntPtr hWnd = Process.GetCurrentProcess().MainWindowHandle;

        SetClassLongPtr(hWnd, GCLP_HICON + ICON_SMALL, icon.Handle);
        SetClassLongPtr(hWnd, GCLP_HICON + ICON_BIG, icon.Handle);
    }
}