为什么此代码在按钮内部工作,而不是在单个过程中？

Question

我正在将原生WiFi API的WinAPI翻译成delphi,我在一个按钮内写了一个rotine进行测试,并且它有效.但是不能在程序中工作,我无法弄清楚为什么因为我只是复制和粘贴.

这个确切的代码是工作

procedure TForm1.Button1Click(Sender: TObject);
var
nVersion:DWORD;
clientHandle:HWND;
return:DWORD;
size:DWORD;
pdata:pWLAN_HOSTED_NETWORK_CONNECTION_SETTINGS;
vtype:pWLAN_OPCODE_VALUE_TYPE;
pfail:PWLAN_HOSTED_NETWORK_REASON;
ssid:array[0..DOT11_SSID_MAX_LENGTH] of UCHAR;
name:String;
begin
    return:=WlanOpenHandle(2,nil,@nVersion,@clientHandle);
    return:=WlanHostedNetworkQueryProperty(clientHandle,wlan_hosted_network_opcode_connection_settings,@size,@pdata,@vtype,nil);
    if return<>ERROR_SUCCESS then ShowMessage('Returned ERROR '+ IntToStr(return));

  name:=Edit1.Text;
    StrCopy(@pdata.hostedNetworkSSID.ucSSID, @name[1]);
    pdata.hostedNetworkSSID.uSSIDLength:=Length(name);

    return:=WlanOpenHandle(2,nil,@nVersion,@clientHandle);
    return:=WlanHostedNetworkSetProperty(clientHandle,wlan_hosted_network_opcode_connection_settings,size,pdata,@pfail,nil);
    if return<>ERROR_SUCCESS then ShowMessage('Returned ERROR '+ IntToStr(return));
end;

但如果将此代码放在另一个程序中以使代码清理并在按钮内调用该函数,则它不起作用!

procedure setSSID(text:String);
var
nVersion:DWORD;
clientHandle:HWND;
return:DWORD;
size:DWORD;
pdata:pWLAN_HOSTED_NETWORK_CONNECTION_SETTINGS;
vtype:pWLAN_OPCODE_VALUE_TYPE;
pfail:PWLAN_HOSTED_NETWORK_REASON;
ssid:array[0..DOT11_SSID_MAX_LENGTH] of UCHAR;
name:String;
begin
    return:=WlanOpenHandle(2,nil,@nVersion,@clientHandle);
    return:=WlanHostedNetworkQueryProperty(clientHandle,wlan_hosted_network_opcode_connection_settings,@size,@pdata,@vtype,nil);
    if return<>ERROR_SUCCESS then ShowMessage('Returned ERROR' + IntToStr(return)); <<<<<< RETURNING ERROR 1734

  name:=text;
    StrCopy(@pdata.hostedNetworkSSID.ucSSID, @name[1]);
    pdata.hostedNetworkSSID.uSSIDLength:=Length(name);

    return:=WlanOpenHandle(2,nil,@nVersion,@clientHandle);
    return:=WlanHostedNetworkSetProperty(clientHandle,wlan_hosted_network_opcode_connection_settings,size,pdata,@pfail,nil);
    if return<>ERROR_SUCCESS then ShowMessage('Returned ERROR '+ IntToStr(return));
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
    setSSID('test');
end;

我收到错误1734后突出显示的行Access violation at address 004084D0 in module Project1.exe. Write of address 000000000.

我只是找不到任何问题,因为代码完全一样!

function WlanHostedNetworkQueryProperty(
  hClientHandle:HANDLE;
  OpCode:WLAN_HOSTED_NETWORK_OPCODE;
  pdwDataSize:PDWORD;
  ppvData:PPVOID;
  pWlanOpcodeValueType:PWLAN_OPCODE_VALUE_TYPE;
  pvReserved:PVOID
):DWORD; stdcall; external 'Wlanapi.dll';


function WlanHostedNetworkSetProperty(
  hClientHandle:HANDLE;
  OpCode:WLAN_HOSTED_NETWORK_OPCODE;
  dwDataSize:DWORD;
  pvData:PVOID;
  pFailReason:PWLAN_HOSTED_NETWORK_REASON;
  pvReserved:PVOID
):DWORD; stdcall; external 'Wlanapi.dll';

---

**OBS:如果我改变路线name:=text;,以name:='hello';它的工程!我仍然不知道为什么,可能是与指针和内存溢出相关的东西.**

Answer 1

WlanHostedNetworkQueryProperty函数的文档声明在调用时必须将pData指针设置为nil.你根本没有初始化它,所以它可能会也可能不会,这取决于堆栈的状态.您需要添加以下行:

pData:= nil;

在通话之前.

您可能希望初始化所有参数.

(抱歉格式不正确,尝试在手机上执行此操作很难!)