程序是这样的:我要问的问题都加了注释!
#include<windows.h>
#include<string.h>
#include<stdlib.h>
#include<stdio.h>
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
//请问上面的定义方法是什么意思定义常量、变量、结构体变量、不是这样的吗?如:int i 上面的定义怎么是LRESULT CALLBACK WndProc这样呢?具体解释一下,还有我还遇到过像这样的如:
hBrush=(HBRUSH)GetStockObject(DKGRAY_BRUSH),我的理解是调用一个函数取得句柄赋值给hBrush,可是函数前面又加个(HBRUSH)是什么意思呀?int WINAPI WinMain //这里定义是怎么回事,定义一个整型的WINAPI还是WinMain呀?
(HINSTANCE hInstance,
HINSTANCE hPrevInst,
LPSTR lpszCmdLine,
int nCmdShow
)
{
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
char lpszClassName[]="映像模式";
char lpszTitle[]="My_Map_Mode"; wndclass.style=0;
wndclass.lpfnWndProc=WndProc;
wndclass.cbClsExtra=0;
wndclass.cbWndExtra=0;
wndclass.hInstance=hInstance;
wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
wndclass.hbrBackground=GetStockObject(WHITE_BRUSH); //***********
wndclass.lpszMenuName=NULL;
wndclass.lpszClassName=lpszClassName;
if(!RegisterClass(&wndclass))
{
MessageBeep(0);
return FALSE;
} hwnd=CreateWindow
(
lpszClassName,
lpszTitle,
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL
);
ShowWindow(hwnd,nCmdShow);
UpdateWindow(hwnd);
while(GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc
(HWND hwnd,
UINT message,
WPARAM wParam,
LPARAM lParam
)
{
HDC hdc;
PAINTSTRUCT ps;
HBRUSH hB1,hB2;
int nMode; switch(message)
{
case WM_CREATE:
nMode=MM_TEXT;
case WM_LBUTTONDOWN:
nMode=MM_ISOTROPIC;
InvalidateRect(hwnd,NULL,1);
break;
case WM_RBUTTONDOWN:
nMode=MM_ANISOTROPIC;
InvalidateRect(hwnd,NULL,1);
break;
case WM_PAINT:
hdc=BeginPaint(hwnd,&ps);
SetMapMode(hdc,nMode);
SetWindowExtEx(hdc,150,150,NULL);
SetViewportExtEx(hdc,150,100,NULL);
SetViewportOrgEx(hdc,150,60,NULL);
hB1=GetStockObject(WHITE_BRUSH); //***********
hB2=GetStockObject(BLACK_BRUSH); //*********
SelectObject(hdc,hB2);
Ellipse(hdc,0,10,150,140);
EndPaint(hwnd,&ps);
break;
case WM_DESTROY:
DeleteObject(hB1);
DeleteObject(hB2);
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd,message,wParam,lParam);
}
return 0;
}以上我加星号的行都产生以下错误!不知道是什么意思!C:\Program Files\Microsoft Visual Studio\MyProjects\TheC_SDK_2\TheC_SDK_2.cpp(92) : error C2440: '=' : cannot convert from 'void *' to 'struct HBRUSH__ *'
Conversion from 'void*' to pointer to non-'void' requires an explicit cast
C:\Program Files\Microsoft Visual Studio\MyProjects\TheC_SDK_2\TheC_SDK_2.cpp(93) : error C2440: '=' : cannot convert from 'void *' to 'struct HBRUSH__ *'
Conversion from 'void*' to pointer to non-'void' requires an explicit cast
#include<windows.h>
#include<string.h>
#include<stdlib.h>
#include<stdio.h>
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
//请问上面的定义方法是什么意思定义常量、变量、结构体变量、不是这样的吗?如:int i 上面的定义怎么是LRESULT CALLBACK WndProc这样呢?具体解释一下,还有我还遇到过像这样的如:
hBrush=(HBRUSH)GetStockObject(DKGRAY_BRUSH),我的理解是调用一个函数取得句柄赋值给hBrush,可是函数前面又加个(HBRUSH)是什么意思呀?int WINAPI WinMain //这里定义是怎么回事,定义一个整型的WINAPI还是WinMain呀?
(HINSTANCE hInstance,
HINSTANCE hPrevInst,
LPSTR lpszCmdLine,
int nCmdShow
)
{
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
char lpszClassName[]="映像模式";
char lpszTitle[]="My_Map_Mode"; wndclass.style=0;
wndclass.lpfnWndProc=WndProc;
wndclass.cbClsExtra=0;
wndclass.cbWndExtra=0;
wndclass.hInstance=hInstance;
wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
wndclass.hbrBackground=GetStockObject(WHITE_BRUSH); //***********
wndclass.lpszMenuName=NULL;
wndclass.lpszClassName=lpszClassName;
if(!RegisterClass(&wndclass))
{
MessageBeep(0);
return FALSE;
} hwnd=CreateWindow
(
lpszClassName,
lpszTitle,
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL
);
ShowWindow(hwnd,nCmdShow);
UpdateWindow(hwnd);
while(GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc
(HWND hwnd,
UINT message,
WPARAM wParam,
LPARAM lParam
)
{
HDC hdc;
PAINTSTRUCT ps;
HBRUSH hB1,hB2;
int nMode; switch(message)
{
case WM_CREATE:
nMode=MM_TEXT;
case WM_LBUTTONDOWN:
nMode=MM_ISOTROPIC;
InvalidateRect(hwnd,NULL,1);
break;
case WM_RBUTTONDOWN:
nMode=MM_ANISOTROPIC;
InvalidateRect(hwnd,NULL,1);
break;
case WM_PAINT:
hdc=BeginPaint(hwnd,&ps);
SetMapMode(hdc,nMode);
SetWindowExtEx(hdc,150,150,NULL);
SetViewportExtEx(hdc,150,100,NULL);
SetViewportOrgEx(hdc,150,60,NULL);
hB1=GetStockObject(WHITE_BRUSH); //***********
hB2=GetStockObject(BLACK_BRUSH); //*********
SelectObject(hdc,hB2);
Ellipse(hdc,0,10,150,140);
EndPaint(hwnd,&ps);
break;
case WM_DESTROY:
DeleteObject(hB1);
DeleteObject(hB2);
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd,message,wParam,lParam);
}
return 0;
}以上我加星号的行都产生以下错误!不知道是什么意思!C:\Program Files\Microsoft Visual Studio\MyProjects\TheC_SDK_2\TheC_SDK_2.cpp(92) : error C2440: '=' : cannot convert from 'void *' to 'struct HBRUSH__ *'
Conversion from 'void*' to pointer to non-'void' requires an explicit cast
C:\Program Files\Microsoft Visual Studio\MyProjects\TheC_SDK_2\TheC_SDK_2.cpp(93) : error C2440: '=' : cannot convert from 'void *' to 'struct HBRUSH__ *'
Conversion from 'void*' to pointer to non-'void' requires an explicit cast
hB2=(HBRUSH*)GetStockObject(BLACK_BRUSH); //*********
void*到hbrush要强制转换
hB1=(HBRUSH)GetStockObject(WHITE_BRUSH); //***********
hB2=(HBRUSH)GetStockObject(BLACK_BRUSH); //*********
因为hB1为hbrush类型,而GetStockObject返回为HGDIOBJ也即为void* 类型
从void*到hbrush要显式转换int WINAPI WinMain //这里定义是怎么回事,定义一个整型的WINAPI还是WinMain呀?
定义一个winmain函数
WINAPI是函数调用的一种约定,等同于__stdcall,该调用约定规定,按从右至左的顺序压参数入栈,由被调用者把参数弹出栈!
Conversion from 'void*' to pointer to non-'void' requires an explicit cast这不是说了么,从void*到非void类型的转换要用显式的强制转换C:\Program Files\Microsoft Visual Studio\MyProjects\TheC_SDK_2\TheC_SDK_2.cpp(93) : error C2440: '=' : cannot convert from 'void *' to 'struct HBRUSH__ *'
Conversion from 'void*' to pointer to non-'void' requires an explicit cast这里也一样就是说你要加上(HBRUSH),表示类型转换啊!
(2)函数的4个参数类型分别是 HWND,UINT,WPARAM,LPARAM
(3)函数的返回值类型是 LRESULT
(4)函数的调用约定是 CALLBACK
函数调用约定是关于函数的参数的传递方法的描述,
关于调用约定更多,参考关于 __stdcall,__fastcall, __cdecl,thiscall 的信息。
hBrush=(HBRUSH)GetStockObject(DKGRAY_BRUSH),我的理解是调用一个函数取得句柄赋值给hBrush,可是函数前面又加个(HBRUSH)是什么意思呀?
答:这里是强制转换
int WINAPI WinMain //这里定义是怎么回事,定义一个整型的WINAPI还是WinMain呀?
答:这是win32的入口函数,就像你在winconsole里面的main函数一样
书不错,我也在学VC,正在看这书.它说了很多MFC内部运作,SDK嘛~呵呵这书开始就讲到了,自己看吧.
可以看一些Windows编程方面的书。先看看简单的VC基础,有个大致的了解,然后再看《深入浅出》理解的就比较快了,这本书不错,应该多看几遍!