Question

哪位C#高手帮忙看一下啊，解释一下代码含义，感激不尽，下面的是部分代码。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace pcscsample
{

public struct SCARD_IO_REQUEST
{
public int dwProtocol;
public int cbPciLength;
}

public partial class pcsc : Form
{

[DllImport("WinSCard.dll")]
public static extern int SCardEstablishContext(uint dwScope, IntPtr pvReserved1, IntPtr pvReserved2, out IntPtr phContext);

[DllImport("WinScard.dll")]
private static extern int SCardConnect(IntPtr hContext, string cReaderName, uint dwShareMode, uint dwPrefProtocol, ref int phCard, ref IntPtr ActiveProtocol);

[DllImport("WinScard.dll", EntryPoint = "SCardListReadersA", CharSet = CharSet.Ansi)]
private static extern int SCardListReaders(IntPtr hContext, string mszGroups, ref StringBuilder mszReaders, ref int pcchReaders);

[DllImport("WinScard.dll")]
private static extern int SCardTransmit(int hCard, ref SCARD_IO_REQUEST pioSendPci, byte[] pbSendBuffer, int cbSendLength, ref SCARD_IO_REQUEST pioRecvPci, ref byte pbRecvBuffer, ref int pcbRecvLength);

[DllImport("WinScard.dll")]
private static extern int SCardDisconnect(int hCard, int Disposition);

[DllImport("WinScard.dll")]
private static extern int SCardReleaseContext(IntPtr phContext);

private const long SCARD_PROTOCOL_T1 = 0x02;
private const uint SCARD_PROTOCOL_T0 = 0x01;
private const long SCARD_S_SUCCESS = 0;
private const uint SCARD_SCOPE_USER = 0;
private const uint SCARD_SHARE_SHARED = 2;

private IntPtr hContext = IntPtr.Zero;
private int hCard = 0;

private string[] readerNameArr;
private string readerNameSelected;

public pcsc()
{
InitializeComponent();
}

Answer 1

//声明结构变量
public struct SCARD_IO_REQUEST
{
public int dwProtocol;
public int cbPciLength;
}

//声明API函数的一些方法你查一下资料就行了
[DllImport("WinSCard.dll")]
public static extern int SCardEstablishContext(uint dwScope, IntPtr pvReserved1, IntPtr pvReserved2, out IntPtr phContext);

[DllImport("WinScard.dll")]
private static extern int SCardConnect(IntPtr hContext, string cReaderName, uint dwShareMode, uint dwPrefProtocol, ref int phCard, ref IntPtr ActiveProtocol);

[DllImport("WinScard.dll", EntryPoint = "SCardListReadersA", CharSet = CharSet.Ansi)]
private static extern int SCardListReaders(IntPtr hContext, string mszGroups, ref StringBuilder mszReaders, ref int pcchReaders);

[DllImport("WinScard.dll")]
private static extern int SCardTransmit(int hCard, ref SCARD_IO_REQUEST pioSendPci, byte[] pbSendBuffer, int cbSendLength, ref SCARD_IO_REQUEST pioRecvPci, ref byte pbRecvBuffer, ref int pcbRecvLength);

[DllImport("WinScard.dll")]
private static extern int SCardDisconnect(int hCard, int Disposition);

[DllImport("WinScard.dll")]
private static extern int SCardReleaseContext(IntPtr phContext);
//声明一些常量
private const long SCARD_PROTOCOL_T1 = 0x02;
private const uint SCARD_PROTOCOL_T0 = 0x01;
private const long SCARD_S_SUCCESS = 0;
private const uint SCARD_SCOPE_USER = 0;
private const uint SCARD_SHARE_SHARED = 2;

private IntPtr hContext = IntPtr.Zero;
private int hCard = 0;

private string[] readerNameArr;
private string readerNameSelected;

//类的构造函数
public pcsc()
{
InitializeComponent();
}

你去查一下API函数怎样用就行了

追问

哦，可以给个扣扣号吗，请教一下，谢谢

追答

1297802639

Answer 2

DllImport：功能是提供从非托管DLL导出的函数的必要调用信息。
DllImport属性应用于方法，要求最少要提供包含入口点的dll的名称。

比如
[DllImport("WinScard.dll")]
private static extern int SCardReleaseContext(IntPtr phContext);
就是声明 来自WinScard这个库中的SCardReleaseContext函数， 这样在C#中你就能直接使用这个函数了。 （因为之前这个函数是外部dll中提供的，C#无法通过类的实例来调用,）

ps:WinScard.dll好像是提供访问智能卡设备的库。

追问

对，就是访问智能卡设备的库，现在我要通过C#来与卡连接，因为第一次接触这个东西，实在不知道怎么下手

追答

你得找智能卡厂商要 API接口说明，知道每个函数以及函数参数的意义，你才会知道怎么使用啊。
看你的代码，需要调用的函数都声明出来了，C#可以直接调用了，
比如这个方法 SCardConnect(IntPtr hContext, string cReaderName, uint dwShareMode, uint dwPrefProtocol, ref int phCard, ref IntPtr ActiveProtocol);
应该是连接智能卡的方法,但是参数怎么传你得看厂商的开发说明书了。
pcsc.SCardConnect(参数1,参数2.....)

追问

谢谢了，可以给个扣扣号码，我的就是我的百度名

Answer 3

i，将i初始化为0，如果i小于数组的位数，i就加1，并且执行中括号中的内容。
如果数组当前的项数不等于用户的属于，那么从数组中把这项删除，并将i减去1.

建议看看算法相关的书。这是程序里最常见的for循环。作用是遍历数组或者一些有二维结构的实体。
另外,团IDC网上有许多产品团购,便宜有口碑