C++技巧(多媒体定时器的简单例子)

1)新建一个项目，保存
2)添加一个按钮和一个标签
3)修改unit1.h代码如下:
/
# ifndef unit 1h
# define unit 1h
/
。include
# include
# include
//
class t form 1:public t form
{
_ _ published://I managed Components
t button * button 1；
t label * label 1；
void _ _ fast call button 1 click(to object * Sender)；
void _ _ fastcall FormCloseQuery(to object * Sender，bool & can close)；
私有://用户声明
公共://用户声明
_ _ fast call t form 1(t component * Owner)；
静态void回调TimeProc(UINT uID，UINT uMsg，
DWORD dwUser，DWORD dw1，DWORD dw2)；//定时器回调函数
int time rid；//考试提示:定时器ID
}；
//
extern PACKAGE t form 1 * form 1；
/
# endif
4)unit 1 . CPP的代码如下:
/
# include
# include " mm system . h "
# pragma hdrstop include " unit 1 . h "
/
# pragma package(smart _ init)
# pragma resource " *。DFM "
t form 1 * form 1；
//
_ _ fast call t form 1::t form 1(t component * Owner)
:t form(Owner)
{
time rid = 0；
}
//
void回调TForm1::TimeProc(UINT uID，UINT uMsg，DWORD dwUser，DWORD dw1，DWORD dw2)
{
form 1 > label 1 > Caption = Now()；
}
//
void _ _ fastcall t form 1::button 1 click(to object * Sender)
{
TIME rid = TIME setevent(1000，0，(LPTIMECALLBACK)TimeProc，0，
TIME _ PERIODIC | TIME _ CALLBACK _ FUNCTION)；//设置多媒体定时器，1000 ms
if(timer ID = = 0){
显示消息("创建失败")；
}
}
//
void _ _ fastcall t form 1::FormCloseQuery(to object * Sender，bool & can close)
{
if(time rid！= 0){
time kill event(time rid)；//释放定时器
}
}
/
操作效果:点击按钮后，Label1开始显示时间。