为什么这段程序不能正常模拟按键？？？急求解答！(15分)

procedure mylogin(user:string;password:string);<br>var<br>u,p:integer;<br>i:Byte;<br>begin<br>u:=length(user);<br>p:=length(password);<br>for u := 1 to u &nbsp;do<br> &nbsp;begin<br> &nbsp; &nbsp;i:=byte(user);<br> &nbsp; &nbsp;keybd_event(i,mapvirtualkey(i,0),0,0);<br> &nbsp; &nbsp;keybd_event(i,mapvirtualkey(i,0),keyeventf_keyup,0);<br> &nbsp; &nbsp;sleep(50);<br> &nbsp;end;<br>end;<br><br>这段程序不能正常按键，mapvirtualkey(i,0)的硬件扫描码老是出错，可是我把i用具体的数字代替又可以正常按键。如：<br>procedure mylogin(user:string;password:string);<br>var<br>u,p:integer;<br>i:Byte;<br>begin<br>u:=length(user);<br>p:=length(password);<br>for u := 1 to u &nbsp;do<br> &nbsp;begin<br> &nbsp; &nbsp;keybd_event(u,mapvirtualkey(u,0),0,0);<br> &nbsp; &nbsp;sleep(10);<br> &nbsp; &nbsp;keybd_event(u,mapvirtualkey(u,0),keyeventf_keyup,0);<br> &nbsp; &nbsp;sleep(50);<br> &nbsp;end;<br>end;<br>这段程序又是正常的，我晕，有高手吗，帮我分析一下，在线等。

for u := 1 to u &nbsp;do????

笔误<br>改成下面的代码，还是不行。<br>procedure mylogin(user:string;password:string);<br>var<br>u,p,j:integer;<br>i:Byte;<br>begin<br>u:=length(user);<br>p:=length(password);<br>for j := 1 to u &nbsp;do<br> &nbsp;begin<br> &nbsp; &nbsp;i:=byte(user[j]);<br> &nbsp; &nbsp;keybd_event(i,mapvirtualkey(i,0),0,0);<br> &nbsp; &nbsp;keybd_event(i,mapvirtualkey(i,0),keyeventf_keyup,0);<br> &nbsp; &nbsp;sleep(50);<br> &nbsp;end;<br>end;

接受答案了.