API的英文全称(Application Programming Interface)，WIN32 API也就是MicrosoftWindows 32位平台的应用程序编程接口。对这个定义的理解，需要追溯到操作系统的发展历史上，当WINDOWS操作系统开始占据主导地位的时候，开发WINDOWS平台下的应用程序成为人们的需要。而在WINDOWS程序设计领域处于发展的初期，WINDOWS程序员所能使用的编程工具唯有API函数，这些函数是WINDOWS提供给应用程序与操作系统的接口，他们犹如“积木块”一样，可以搭建出各种界面丰富，功能灵活的应用程序。所以可以认为API函数是构筑整个WINDOWS框架的基石，在它的下面是WINDOWS的操作系统核心，而它的上面则是所有的华丽的WINDOWS应用程序。
什么是Windows API函数
#include <winapifamily.h>
/*++ BUILD Version: 0001 Increment this if a change has global effects
Copyright (c) Microsoft Corporation. All rights reserved.
Module Name:
windows.h
Abstract:
Master include file for Windows applications.
--*/
#ifndef _WINDOWS_
#define _WINDOWS_
#include <sdkddkver.h>
#ifndef _INC_WINDOWS
#define _INC_WINDOWS
#if defined (_MSC_VER) && (_MSC_VER >= 1020)
#pragma once
#endif
#pragma region Application Family
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP)
/* If defined, the following flags inhibit definition
* of the indicated items.
*
* NOGDICAPMASKS - CC_*, LC_*, PC_*, CP_*, TC_*, RC_
* NOVIRTUALKEYCODES - VK_*
* NOWINMESSAGES - WM_*, EM_*, LB_*, CB_*
* NOWINSTYLES - WS_*, CS_*, ES_*, LBS_*, SBS_*, CBS_*
* NOSYSMETRICS - SM_*
* NOMENUS - MF_*
* NOICONS - IDI_*
* NOKEYSTATES - MK_*
* NOSYSCOMMANDS - SC_*
* NORASTEROPS - Binary and Tertiary raster ops
* NOSHOWWINDOW - SW_*
* OEMRESOURCE - OEM Resource values
* NOATOM - Atom Manager routines
* NOCLIPBOARD - Clipboard routines
* NOCOLOR - Screen colors
* NOCTLMGR - Control and Dialog routines
* NODRAWTEXT - DrawText() and DT_*
* NOGDI - All GDI defines and routines
* NOKERNEL - All KERNEL defines and routines
* NOUSER - All USER defines and routines
* NONLS - All NLS defines and routines
* NOMB - MB_* and MessageBox()
* NOMEMMGR - GMEM_*, LMEM_*, GHND, LHND, associated routines
* NOMETAFILE - typedef METAFILEPICT
* NOMINMAX - Macros min(a,b) and max(a,b)
* NOMSG - typedef MSG and associated routines
* NOOPENFILE - OpenFile(), OemToAnsi, AnsiToOem, and OF_*
* NOSCROLL - SB_* and scrolling routines
* NOSERVICE - All Service Controller routines, SERVICE_ equates, etc.
* NOSOUND - Sound driver routines
* NOTEXTMETRIC - typedef TEXTMETRIC and associated routines
* NOWH - SetWindowsHook and WH_*
* NOWINOFFSETS - GWL_*, GCL_*, associated routines
* NOCOMM - COMM driver routines
* NOKANJI - Kanji support stuff.
* NOHELP - Help engine interface.
* NOPROFILER - Profiler interface.
* NODEFERWINDOWPOS - DeferWindowPos routines
* NOMCX - Modem Configuration Extensions
*/
#if defined(RC_INVOKED) && !defined(NOWINRES)
#include <winresrc.h>
#else
#if defined(RC_INVOKED)
/* Turn off a bunch of stuff to ensure that RC files compile OK. */
#define NOATOM
#define NOGDI
#define NOGDICAPMASKS
#define NOMETAFILE
#define NOMINMAX
#define NOMSG
#define NOOPENFILE
#define NORASTEROPS
#define NOSCROLL
#define NOSOUND
#define NOSYSMETRICS
#define NOTEXTMETRIC
#define NOWH
#define NOCOMM
#define NOKANJI
#define NOCRYPT
#define NOMCX
#endif
#if !defined(_68K_) && !defined(_MPPC_) && !defined(_X86_) && !defined(_IA64_) && !defined(_AMD64_) && !defined(_ARM_) && defined(_M_IX86)
#define _X86_
#endif
#if !defined(_68K_) && !defined(_MPPC_) && !defined(_X86_) && !defined(_IA64_) && !defined(_AMD64_) && !defined(_ARM_) && defined(_M_AMD64)
#define _AMD64_
#endif
#if !defined(_68K_) && !defined(_MPPC_) && !defined(_X86_) && !defined(_IA64_) && !defined(_AMD64_) && !defined(_ARM_) && defined(_M_ARM)
#define _ARM_
#endif
#if !defined(_68K_) && !defined(_MPPC_) && !defined(_X86_) && !defined(_IA64_) && !defined(_AMD64_) && !defined(_ARM_) && defined(_M_M68K)
#define _68K_
#endif
#if !defined(_68K_) && !defined(_MPPC_) && !defined(_X86_) && !defined(_IA64_) && !defined(_AMD64_) && !defined(_ARM_) && defined(_M_MPPC)
#define _MPPC_
#endif
#if !defined(_68K_) && !defined(_MPPC_) && !defined(_X86_) && !defined(_M_IX86) && !defined(_AMD64_) && !defined(_ARM_) && defined(_M_IA64)
#if !defined(_IA64_)
#define _IA64_
#endif /* !_IA64_ */
#endif
#ifndef _MAC
#if defined(_68K_) || defined(_MPPC_)
#define _MAC
#endif
#endif
#if defined (_MSC_VER)
#if ( _MSC_VER >= 800 )
#ifndef __cplusplus
#pragma warning(disable:4116) /* TYPE_ALIGNMENT generates this - move it */
/* outside the warning push/pop scope. */
#endif
#endif
#endif
#ifndef RC_INVOKED
#if ( _MSC_VER >= 800 )
#pragma warning(disable:4514)
#ifndef __WINDOWS_DONT_DISABLE_PRAGMA_PACK_WARNING__
#pragma warning(disable:4103)
#endif
#if _MSC_VER >= 1200
#pragma warning(push)
#endif
#pragma warning(disable:4001)
#pragma warning(disable:4201)
#pragma warning(disable:4214)
#endif
#include <excpt.h>
#include <stdarg.h>
#endif /* RC_INVOKED */
#include <windef.h>
#include <winbase.h>
#include <wingdi.h>
#include <winuser.h>
#if !defined(_MAC) || defined(_WIN32NLS)
#include <winnls.h>
#endif
#ifndef _MAC
#include <wincon.h>
#include <winver.h>
#endif
#if !defined(_MAC) || defined(_WIN32REG)
#include <winreg.h>
#endif
#ifndef _MAC
#include <winnetwk.h>
#endif
#ifndef WIN32_LEAN_AND_MEAN
#include <cderr.h>
#include <dde.h>
#include <ddeml.h>
#include <dlgs.h>
#ifndef _MAC
#include <lzexpand.h>
#include <mmsystem.h>
#include <nb30.h>
#include <rpc.h>
#endif
#include <shellapi.h>
#ifndef _MAC
#include <winperf.h>
#include <winsock.h>
#endif
#ifndef NOCRYPT
#include <wincrypt.h>
#include <winefs.h>
#include <winscard.h>
#endif
#ifndef NOGDI
#ifndef _MAC
#include <winspool.h>
#ifdef INC_OLE1
#include <ole.h>
#else
#include <ole2.h>
#endif /* !INC_OLE1 */
#endif /* !MAC */
#include <commdlg.h>
#endif /* !NOGDI */
#endif /* WIN32_LEAN_AND_MEAN */
#include <stralign.h>
#ifdef _MAC
#include <winwlm.h>
#endif
#ifdef INC_OLE2
#include <ole2.h>
#endif /* INC_OLE2 */
#ifndef _MAC
#ifndef NOSERVICE
#include <winsvc.h>
#endif
#if(WINVER >= 0x0400)
#ifndef NOMCX
#include <mcx.h>
#endif /* NOMCX */
#ifndef NOIME
#include <imm.h>
#endif
#endif /* WINVER >= 0x0400 */
#endif
#ifndef RC_INVOKED
#if ( _MSC_VER >= 800 )
#if _MSC_VER >= 1200
#pragma warning(pop)
#else
#pragma warning(default:4001)
#pragma warning(default:4201)
#pragma warning(default:4214)
/* Leave 4514 disabled. It's an unneeded warning anyway. */
#endif
#endif
#endif /* RC_INVOKED */
#endif /* RC_INVOKED */
#endif /* WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP) */
#pragma endregion
#endif /* _INC_WINDOWS */
#endif /* _WINDOWS_ */
windows.h文件
// Win32Project1.cpp : 定义应用程序的入口点。
//
#include "stdafx.h"
#include "Win32Project1.h"
#define MAX_LOADSTRING 100
// 全局变量:
HINSTANCE hInst; // 当前实例
WCHAR szTitle[MAX_LOADSTRING]; // 标题栏文本
WCHAR szWindowClass[MAX_LOADSTRING]; // 主窗口类名
// 此代码模块中包含的函数的前向声明:
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);
int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
_In_ int nCmdShow)
{
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpCmdLine);
// TODO: 在此放置代码。
// 初始化全局字符串
LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadStringW(hInstance, IDC_WIN32PROJECT1, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
// 执行应用程序初始化:
if (!InitInstance (hInstance, nCmdShow))
{
return FALSE;
}
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_WIN32PROJECT1));
MSG msg;
// 主消息循环:
while (GetMessage(&msg, nullptr, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int) msg.wParam;
}
//
// 函数: MyRegisterClass()
//
// 目的: 注册窗口类。
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEXW wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WIN32PROJECT1));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_WIN32PROJECT1);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassExW(&wcex);
}
//
// 函数: InitInstance(HINSTANCE, int)
//
// 目的: 保存实例句柄并创建主窗口
//
// 注释:
//
// 在此函数中，我们在全局变量中保存实例句柄并
// 创建和显示主程序窗口。
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
hInst = hInstance; // 将实例句柄存储在全局变量中
HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);
if (!hWnd)
{
return FALSE;
}
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
return TRUE;
}
//
// 函数: WndProc(HWND, UINT, WPARAM, LPARAM)
//
// 目的: 处理主窗口的消息。
//
// WM_COMMAND - 处理应用程序菜单
// WM_PAINT - 绘制主窗口
// WM_DESTROY - 发送退出消息并返回
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_COMMAND:
{
int wmId = LOWORD(wParam);
// 分析菜单选择:
switch (wmId)
{
case IDM_ABOUT:
DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
}
break;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
// TODO: 在此处添加使用 hdc 的任何绘图代码...
EndPaint(hWnd, &ps);
}
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
// “关于”框的消息处理程序。
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
UNREFERENCED_PARAMETER(lParam);
switch (message)
{
case WM_INITDIALOG:
return (INT_PTR)TRUE;
case WM_COMMAND:
if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
{
EndDialog(hDlg, LOWORD(wParam));
return (INT_PTR)TRUE;
}
break;
}
return (INT_PTR)FALSE;
}