请帮忙看一下这个DLL调用的函数，参数怎么写

2010-07-23 12:08:02 203 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

C#调用非托管DLL函数一概念运行时处于控制之下的代码称为托管代码，反之，在运行环境（runtime）之外运行的代码称为非托管代码。平台调用(来自consuming unmanaged dll functions)是一个可以使托管代码调用在DLL中实现的非托管函数，例如那些win32 API。它找到和调用导出的函数，同时根据需要将函数的参数（整形，字符，数组，结构体等等）通过互操作边界（interopera 阅读详情

pisn_getsnapshots
This function retrieves the most recent values sent to the pi System for an array of points. The snapshot values in engineering units, status codes, times, dates, and errors are returned in the passed parallel arrays. If the point type is not real, the value is returned in istat and the rval argument is returned as 0.

C format

int32 pisn_getsnapshots(
int32 PIPTR * pt
float PIPTR * rval,
int32 PIPTR * istat,
int32 PIPTR * timedate,
int32 PIPTR * error,
int32 count );
Returns
>0
System error
0
Success
-1
Point not found

Arguments
pt (passed)
Array of point numbers
rval (returned)
Array of values in engineering units, undefined for integer and digital points
istat (returned)
Array of statuses for type real points and values for integer and digital points
timedate (returned)
array of time stamps
error (returned)
Array of error codes
count(passed)
Size of the arrays
pi Toolkit Reference
GetSnapshot

以下是VB的定义
Declare Function pisn_getsnapshots Lib "piapi32.dll" (pt&, rval!, istat&, timedate&, piapierror&, ByVal count&) As Long

我是这样定义的
function pisn_getsnapshots(pt:array of Integer;rval:array of single;istat:array of Integer; timedate:array of Integer; error:array of Integer; count: Integer):Integer;stdcall;external 'piapi32.dll';

调用的时候
var
pt:array[0..20] of Integer;
rval:array[0..20] of single;
istat:array[0..20] of Integer;
timedatePt:array[0..20] of Integer;
errorPt:array[0..20] of Integer;
countPt: Integer

i:=getsnapshots(pt[0],rval[0],istat[0],timedatePt[0],errorPt[0],countPt);

i的值为0表示调用成功，但是rval[0]。。rval[20],的值都不正常，我把上面的句函数调用注释掉，rval[0]..ravl[20]的值仍不变，证明rval的数值在函数中没有被赋值，请高手帮忙看一下，是不是我的定义有问题，还是调用方法有问题

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