如何让IntPtr指向一个字符串

[yooono]

IntPtr idp= IntPtr.Zero;
StringBuilder idata = new StringBuilder("000000");
string idata ="000000";
我这样建立的2个idata字符串，如何让idp指向他
我指向他的目的是为了传递给dll的某个函数，他需要传指针
还有我定义了一个结构如何向dll的函数传递其指针？
http://community.csdn.net/Expert/topic/5612/5612998.xml?temp=.9482843

http://community.csdn.net/Expert/topic/5614/5614773.xml?temp=.5012018
所有分了，解决一起结了。

[兔子-顾问]

char[] charArray = StringBuilder.ToString().ToCharArray();
unsafe
{
fixed(char* p = &charArray[0])
{
//p就是字串首地址
}
}

[蒋晟]

http://msdn2.microsoft.com/en-us/library/s97shtze(VS.80).aspx

[CSharpEx]

mark

[yooono]

郁闷好几天了，顶下

[王集鹄]

//参考标准API如何实现的

[DllImport("user32.dll")]
public static extern int GetWindowText(IntPtr hWnd,
StringBuilder lpString, int nMaxCount);

private void button1_Click(object sender, EventArgs e)
{
StringBuilder vStringBuilder = new StringBuilder(256);
GetWindowText(Handle, vStringBuilder, vStringBuilder.Capacity);
Console.WriteLine(vStringBuilder.ToString());
}

[killer_liqiao]

怎么一点都不懂~~~
UP

[wzd24]

用GCHandle.Alloc（object obj)方法来给string分配一个指针！

[yooono]

to zswang(伴水清清)(专家门诊清洁工) :
我想用IntPtr取出当前字符串的指针然后传递到我将要用到的dll函数中，然后这个dll函数会根据这指针对这个StringBuilder 进行读取写入操作，然后返回其值c#环境中进行操作
==============================================
指向StringBuilder 暂时先不管他，因为我用IntPtr idp= IntPtr.Zero;
这idp是0得值也可以调用该函数，而且这函数返回值我先略过去
现在我想让IntPtr idp= IntPtr.Zero作为一个结构的指针传递到dll中去又出现问题了。
问题估计是一种情况，就是我在c#里声明的无论字符串也好结构也好，哪怕传递了ref 进去照样是"写保护"的，dll是无法进行写操作的，我该怎么往里传递呢？

[wzd24]

能不能把你的DLL拿过来让我看看？？

[yooono]

可以，怎么联系你呀

[yooono]

qq:465731031我的

[yooono]

public struct CINFTBL
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 6)]
public String htid;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 2)]
public String htdmy;
public long adv;
public long fileno;
public long filesize;
public long jobcmd;
public long datatype;
}

这结构
函数里面需要调用c原形这样

Function :
After polling, acquire the table data stored the communication management information. When the first data after polling is acquired, call this command. Call hst_getcinfnext by the next programming.
Form：
int hst_getcinffirst(CINFTBL *cinftbl)
Parameter：
typedef struct CINFTBL { Data acquirement territory for the stored table of the
communication management information.
UCHAR htid[6] ID letter line
Set ID letter line of dt700/750 in sending management.
UCHAR htdmy[2] Dummy
This command is no meaning.
long adv Priority Order
Priority order is set.
long fileno File number
Set the sending file number in requesting the sending file from dt700/750.
long filesize Total of file size
Set the total sending file in requesting the sending file from dt700/750.
long jobcmd Management request command
Set the management command requested from dt700/750 in establishing the
data linking.
0:file receiving(PC←HT)、1:file sending(PC→HT)、
255:cutting request
long datatype Kind of data
Set the kind of the objected data requested the management fromdt700/750.
} cinftbl

[bote_china]

.net里API调用没有必要考虑字符串指针吧？应该定义为stirng就可以，结构也是如此，只要自定义结构中的元素和API的保持一致就行。你可以参考一下.net框架的基类是如何调用API的,比如常见的事件消息MSG结构是如何定义的,GDI绘图中用到的rect结构是如何定义和使用的。界面API的封装在System.Windows.Forms.UnsafeNaiveMethods类中,需要用反编工具才能查看。

[yooono]

这个字符串dll会读取修改并返回给c#的，用string 会被写保护的

[bote_china]

举个例子
[DllImport("user32.dll")]
public static extern IntPtr SendMessage(HandleRef hWnd, int msg, ref int wParam, ref int lParam)；
如果Api方法需要返回这个参数，那么就用ref string paramname来定义参数。

[wzd24]

结贴！！结贴！！

[yooono]

555555

[yooono]

没分了

[soupsea]

String s = "Hello";
IntPtr p = Marshal.StringToHGlobalAnsi(s);