更新时间:2016-01-01 19:37:05浏览次数:1+次
我们删除字符串的效果如下图所示:
if (VK_BACK==wParam)
{
int len = lstrlen(cjjjs);
if (len!=0)
{
cjjjs[len-1]=_T(');
}
}
TextOut(hdc,0,0,cjjjs,lstrlen(cjjjs));
InvalidateRect(hwnd,NULL,TRUE);
从代码可以看到,TextOut始终都是显示字符串cjjjs,改变的只是原始的字符串而已。static int iDelCount=0;
iDelCount++;
TextOut(hdc,0,0,cjjjs,lstrlen(cjjjs)-iDelCount);
InvalidateRect(hwnd,NULL,TRUE);
从代码中可以看出,原始的字符串并没有改变,每次删除只是对删除的字符数计数,然后在TextOut输出时,减少输出的字符数,从而达到删除的效果。#include "windows.h"
#include <tchar.h>
// - 项目是Unicode字符集
TCHAR cjjjs[100]=_T("C++技术网http:www.cjjjs.com");
TCHAR tip[100]=_T("提示:按下键盘的←(退格键)可以删除了字符");
LRESULT CALLBACK WinProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
HDC hdc;
PAINTSTRUCT ps;
static RECT rect;
static int iDelCount=0;
switch (message)
{
case WM_PAINT:
hdc = BeginPaint(hwnd,&ps);
SelectObject(hdc,GetStockObject(SYSTEM_FIXED_FONT));
TextOut(hdc,0,0,cjjjs,lstrlen(cjjjs)-iDelCount);
TextOut(hdc,0,50,tip,lstrlen(tip));
EndPaint(hwnd,&ps);
return 0;
case WM_KEYDOWN:
if (VK_BACK==wParam)
{
//直接在原字符串上删除
int len = lstrlen(cjjjs);
if (len!=0)
{
cjjjs[len-1]=_T(');
}
//只是减少显示的字符个数,原字符串不受影响
//iDelCount++;
}
InvalidateRect(hwnd,NULL,TRUE);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
default:
return DefWindowProc(hwnd, message, wParam, lParam);
}
}
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrev,LPSTR lpCmd,int iShow)
{
TCHAR ClassName[] = _T("MyClass");
TCHAR title1[] = _T("C++技术网http://www.cjjjs.com");
WNDCLASS wndClass;
wndClass.cbClsExtra=0;
wndClass.cbWndExtra=0;
wndClass.hbrBackground= (HBRUSH)GetStockObject(WHITE_BRUSH);
wndClass.hCursor=LoadCursor(NULL,IDC_HAND);
wndClass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
wndClass.hInstance = hInstance;
wndClass.lpfnWndProc = WinProc;
wndClass.lpszClassName = ClassName;
wndClass.lpszMenuName=NULL;
wndClass.style=CS_HREDRAW|CS_VREDRAW;
if(!RegisterClass(&wndClass))return 0;
HWND hwnd = CreateWindow(ClassName,title1,WS_OVERLAPPEDWINDOW,0,0,440,400,NULL,NULL,hInstance,NULL);
ShowWindow(hwnd,SW_SHOWNORMAL);
MSG msg;
while (GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
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