C # calls C + + platform invoke p/invoke struct--input and output parameters, return value, rebate value, struct array as parameter "five"

"1" structure as input and output parameters

C + + code:

typedef struct _TESTSTRU1{INTIVAL;CHARCVAL;__INT64 Llval;} TESTSTRU1;

Exportdll_api void Struct_change (testStru1 *pstru) {if (NULL = = Pstru) {return;} Pstru->ival = 1;pstru->cval = ' a ';p stru->llval = 2;wprintf (L "struct_change \ n");}

C # code: specified as ref

/*   1. Mark the structure with StructLayout, specify the structure body storage layout *   2. The order of field definitions  *   3. Field type  *   4. The size of the field in memory  *   5. unmanaged and managed struct names can be different  *///4.1 struct as input/output parameter [StructLayout (LayoutKind.Sequential, CharSet=CharSet.Unicode)]public struct teststru1{public   intival;   Public sbyte    Cval;   public long      llval;}; [DllImport ("ExportDll.dll", CharSet = charset.unicode)]public static extern void Struct_change (ref testStru1 Pstru);

Test:

CEXPORTDLL.TESTSTRU1 stru1 = new Cexportdll.teststru1 (); Cexportdll.struct_change (ref STRU1);

"2" struct as return value

C + + code:

typedef struct _TESTSTRU5{INTIVAL;} Teststru5;teststru5g_stru5;

Exportdll_api teststru5* Struct_return () {g_stru5.ival = 5;wprintf (L "Struct_return \ n"); Return (&G_STRU5);}

C # code, define a return value of IntPtr, and then parse:

[StructLayout (LayoutKind.Sequential, charset=charset.unicode)]public struct teststru5{public    intival;}; [DllImport ("ExportDll.dll", CharSet = charset.unicode)]public static extern IntPtr Struct_return ();

Test:

IntPtr struintptr = Cexportdll.struct_return (); Cexportdll.teststru5 Stru5 = (cexportdll.teststru5) (Marshal.PtrToStructure (Struintptr, typeof (Cexportdll.teststru5 )));

"3" struct array as a parameter

C + + code:

typedef struct _TESTSTRU6{INTIVAL;} TestStru6;

Exportdll_api void Struct_struarr (testStru6 *pstru, int len) {if (NULL = = Pstru) {return;} for (int ix=0; ix<len; ix++) {pstru[ix].ival = IX;} wprintf (L "Struct_struarr \ n");}

C # code: defined as teststru6[], if you need to return the modified value, you need to specify the [in,out] parameter

[StructLayout (LayoutKind.Sequential, charset=charset.unicode)]public struct teststru6{public    intival;}; [DllImport ("ExportDll.dll", CharSet = charset.unicode)]public static extern void Struct_struarr ([In, out]teststru6[] Pstru, int len);

Test:

Cexportdll.teststru6 []STRU6 = new cexportdll.teststru6[5]; Cexportdll.struct_struarr (Stru6, 5);

"4" struct as a rebate parameter, releasing unmanaged memory

C + + code:

typedef struct _TESTSTRU8{INTM;} TestStru8;

Exportdll_api void Struct_parameterout (TestStru8 **ppstru) {if (NULL = = Ppstru) {return;} *ppstru = (teststru8*) cotaskmemalloc (sizeof (TESTSTRU8));(*ppstru)->m= 8;wprintf (L "struct_parameterout \ n");}

C # code: can be defined as ref IntPtr, need to parse

[StructLayout (LayoutKind.Sequential, charset=charset.unicode)]public struct teststru8{public    intm;}; [DllImport ("ExportDll.dll", CharSet = charset.unicode)]public static extern void Struct_parameterout (ref IntPtr Ppstru) ;

Test:

<strong>intptr outptr = IntPtr.Zero; Cexportdll.struct_parameterout (ref outptr); Cexportdll.teststru8 stru8 = (cexportdll.teststru8) (Marshal.PtrToStructure (Outptr, typeof (Cexportdll.teststru8))); Marshal.freecotaskmem (outptr);</strong>

C # calls C + + platform invoke p/invoke struct--input and output parameters, return value, rebate value, struct array as parameter "five"