C++ 如何通过 DLL 在 Ada 和 C 之间传递复杂数据类型，例如记录

我正在try 让Ada代码编译成可在C中调用的DLL，到目前为止，我已经设法使其适用于简单类型，如整数，但对于更复杂的类型，如数组或记录/ struct ，我遇到了困难.

下面是我的记录/ struct 的Ada代码.它是一个动态库，我使用命令"gprBuild-p../Math.gpr-p"将其编译为DLL:

person.adb
with Interfaces.C; use Interfaces.C;

package body Person is

   function Set_Age_To_Five(P : Person_Record) return Person_Record is
      Result : Person_Record;
   begin
      Result := P;
      Result.Age := 5;
      return Result;
   end Set_Age_To_Five;

end Person;

Person.ads

with Interfaces.C; use Interfaces.C;

package Person is

   type Person_Record is record
      Name    : String(1 .. 100);
      Age     : Interfaces.C.int;
      Address : String(1 .. 100);
   end record with Convention => C_Pass_By_Copy;

   function Set_Age_To_Five(P : Person_Record) return Person_Record;
   pragma Export (C, Set_Age_To_Five, "Set_Age_To_Five");

end Person;

Math.gpr

library project Math is
    for Languages use ("Ada");
    for Library_Name use "Person";
    for Source_Dirs use ("src");
    for Object_Dir use "obj";
    for Library_Dir use "lib";
    for Library_Kind use "Dynamic";
end Math;

然后我有一个C头文件math.h:

#ifndef MATH_H
#define MATH_H

#ifdef __cplusplus
extern "C"
#endif

typedef struct {
    char Name[101];
    int Age;
    char Address[101];
} Person_Record;

Person_Record Set_Age_To_Five(Person_Record P);

#ifdef __cplusplus

#endif

#endif /* MATH_H */

最后是我的C代码:

#include <stdio.h>
#include "math.h"

int main() {
    Person_Record p, q, r;

    // Initialize the person record
    snprintf(p.Name, sizeof(p.Name), "John");
    p.Age = 25;
    snprintf(p.Address, sizeof(p.Address), "123 Main St");

    // Call the Set_Age_To_Five function from the DLL
    q = Set_Age_To_Five(p);

    // Print the modified person record
    printf("Name: %s\n", q.Name);
    printf("Age: %d\n", q.Age);
    printf("Address: %s\n", q.Address);

    return 0;
}

这在执行时应该返回

Name: John
Age: 5
Address: 123 Main St

相反，它的回归:

Name: John
Age: 25
Address: 123 Main St

我try 过通过变量传递，通过引用传递.在ADA中使用约定C和约定传递c.