如何：在 C++/CLI 中使用数组

项目
03/12/2013

本文在 C++/CLI描述如何使用数组。

一维数组

下面的示例演示如何创建一维数组引用，值和本机指针类型。它还演示如何返回从函数的单维数组以及如何传递一维数组作为参数传递给函数。

// mcppv2_sdarrays.cpp
// compile with: /clr
using namespace System;

#define ARRAY_SIZE 2

value struct MyStruct {
   int m_i;
};

ref class MyClass {
public:
   int m_i;
};

struct MyNativeClass {
   int m_i;
};

// Returns a managed array of a reference type.
array<MyClass^>^ Test0() {
   int i;
   array< MyClass^ >^ local = gcnew array< MyClass^ >(ARRAY_SIZE);

   for (i = 0 ; i < ARRAY_SIZE ; i++) {
      local[i] = gcnew MyClass;
      local[i] -> m_i = i;
   }
   return local;
}


// Returns a managed array of Int32.
array<Int32>^ Test1() {
   int i;
   array< Int32 >^ local = gcnew array< Int32 >(ARRAY_SIZE);

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      local[i] = i + 10;
   return local;
}


// Modifies an array.
void Test2(array< MyNativeClass * >^ local) {
   for (int i = 0 ; i < ARRAY_SIZE ; i++)
      local[i] -> m_i = local[i] -> m_i + 2;
}

int main() {
   int i;

   // Declares an array of user-defined reference types
   // and uses a function to initialize.
   array< MyClass^ >^ MyClass0;
   MyClass0 = Test0();

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      Console::WriteLine("MyClass0[{0}] = {1}", i, MyClass0[i] -> m_i);
   Console::WriteLine();


   // Declares an array of value types and uses a function to initialize.
   array< Int32 >^ IntArray;
   IntArray = Test1();

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      Console::WriteLine("IntArray[{0}] = {1}", i, IntArray[i]);
   Console::WriteLine();


   // Declares and initializes an array of user-defined 
   // reference types.
   array< MyClass^ >^ MyClass1 = gcnew array< MyClass^ >(ARRAY_SIZE);
   for (i = 0 ; i < ARRAY_SIZE ; i++) {
      MyClass1[i] = gcnew MyClass;
      MyClass1[i] -> m_i = i + 20;
   }

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      Console::WriteLine("MyClass1[{0}] = {1}", i, MyClass1[i] -> m_i);
   Console::WriteLine();


   // Declares and initializes an array of pointers to a native type.
   array< MyNativeClass * >^ MyClass2 = gcnew array< 
      MyNativeClass * >(ARRAY_SIZE);
   for (i = 0 ; i < ARRAY_SIZE ; i++) {
      MyClass2[i] = new MyNativeClass();
      MyClass2[i] -> m_i = i + 30;
   }

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      Console::WriteLine("MyClass2[{0}] = {1}", i, MyClass2[i]->m_i);
   Console::WriteLine();

   Test2(MyClass2);
   for (i = 0 ; i < ARRAY_SIZE ; i++)
      Console::WriteLine("MyClass2[{0}] = {1}", i, MyClass2[i]->m_i);
   Console::WriteLine();

   delete[] MyClass2[0];
   delete[] MyClass2[1];

   // Declares and initializes an array of user-defined value types.
   array< MyStruct >^ MyStruct1 = gcnew array< MyStruct >(ARRAY_SIZE);
   for (i = 0 ; i < ARRAY_SIZE ; i++) {
      MyStruct1[i] = MyStruct();
      MyStruct1[i].m_i = i + 40;
   }

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      Console::WriteLine("MyStruct1[{0}] = {1}", i, MyStruct1[i].m_i);
}

Output

下一个示例演示如何对一维托管数组的聚合初始化。

// mcppv2_sdarrays_aggregate_init.cpp
// compile with: /clr
using namespace System;

ref class G {
public:
   G(int i) {}
};

value class V {
public:
   V(int i) {}
};

class N {
public:
   N(int i) {}
};

int main() {
   // Aggregate initialize a single-dimension managed array.
   array<String^>^ gc1 = gcnew array<String^>{"one", "two", "three"};
   array<String^>^ gc2 = {"one", "two", "three"};

   array<G^>^ gc3 = gcnew array<G^>{gcnew G(0), gcnew G(1), gcnew G(2)};
   array<G^>^ gc4 = {gcnew G(0), gcnew G(1), gcnew G(2)};   

   array<Int32>^ value1 = gcnew array<Int32>{0, 1, 2};
   array<Int32>^ value2 = {0, 1, 2};

   array<V>^ value3 = gcnew array<V>{V(0), V(1), V(2)};
   array<V>^ value4 = {V(0), V(1), V(2)};

   array<N*>^ native1 = gcnew array<N*>{new N(0), new N(1), new N(2)};
   array<N*>^ native2 = {new N(0), new N(1), new N(2)};
}

Output

此示例演示如何针对多维度托管数组的聚合初始化：

// mcppv2_mdarrays_aggregate_initialization.cpp
// compile with: /clr
using namespace System;

ref class G {
public:
   G(int i) {}
};

value class V {
public:
   V(int i) {}
};

class N {
public:
   N(int i) {}
};

int main() {
   // Aggregate initialize a multidimension managed array.
   array<String^, 2>^ gc1 = gcnew array<String^, 2>{ {"one", "two"}, 
       {"three", "four"} };
   array<String^, 2>^ gc2 = { {"one", "two"}, {"three", "four"} };

   array<G^, 2>^ gc3 = gcnew array<G^, 2>{ {gcnew G(0), gcnew G(1)}, 
       {gcnew G(2), gcnew G(3)} };
   array<G^, 2>^ gc4 = { {gcnew G(0), gcnew G(1)}, {gcnew G(2), gcnew G(3)} };

   array<Int32, 2>^ value1 = gcnew array<Int32, 2>{ {0, 1}, {2, 3} };
   array<Int32, 2>^ value2 = { {0, 1}, {2, 3} };

   array<V, 2>^ value3 = gcnew array<V, 2>{ {V(0), V(1)}, {V(2), V(3)} };
   array<V, 2>^ value4 = { {V(0), V(1)}, {V(2), V(3)} };

   array<N*, 2>^ native1 = gcnew array<N*, 2>{ {new N(0), new N(1)}, 
      {new N(2), new N(3)} };
   array<N*, 2>^ native2 = { {new N(0), new N(1)}, {new N(2), new N(3)} };
}

交错数组

本节演示如何创建一维托管数组引用，值和本机指针类型。它还演示如何返回一维从函数的托管数组以及如何传递一维数组作为参数传递给函数。

// mcppv2_array_of_arrays.cpp
// compile with: /clr
using namespace System;

#define ARRAY_SIZE 2

value struct MyStruct {
   int m_i;
};

ref class MyClass {
public:
   int m_i;
};

// Returns an array of managed arrays of a reference type.
array<array<MyClass^>^>^ Test0() {
   int size_of_array = 4;
   array<array<MyClass^>^>^ local = gcnew 
      array<array<MyClass^>^>(ARRAY_SIZE);

   for (int i = 0 ; i < ARRAY_SIZE ; i++, size_of_array += 4) {
      local[i] = gcnew array<MyClass^>(size_of_array);
      for (int k = 0; k < size_of_array ; k++) {
         local[i][k] = gcnew MyClass;
         local[i][k] -> m_i = i;
      }
   }

   return local;
}

// Returns a managed array of Int32.
array<array<Int32>^>^ Test1() {
   int i;
   array<array<Int32>^>^ local = gcnew array<array< Int32 >^>(ARRAY_SIZE);

   for (i = 0 ; i < ARRAY_SIZE ; i++) {
      local[i] = gcnew array< Int32 >(ARRAY_SIZE);
         for ( int j = 0 ; j < ARRAY_SIZE ; j++ ) 
            local[i][j] = i + 10;
   }
   return local;
}

int main() {
   int i, j;

   // Declares an array of user-defined reference types
   // and uses a function to initialize.
   array< array< MyClass^ >^ >^ MyClass0;
   MyClass0 = Test0();

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      for ( j = 0 ; j < ARRAY_SIZE ; j++ ) 
         Console::WriteLine("MyClass0[{0}] = {1}", i, MyClass0[i][j] -> m_i);
   Console::WriteLine();


   // Declares an array of value types and uses a function to initialize.
   array< array< Int32 >^ >^ IntArray;
   IntArray = Test1();

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      for (j = 0 ; j < ARRAY_SIZE ; j++)
      Console::WriteLine("IntArray[{0}] = {1}", i, IntArray[i][j]);
   Console::WriteLine();

   // Declares and initializes an array of user-defined value types.
   array< MyStruct >^ MyStruct1 = gcnew array< MyStruct >(ARRAY_SIZE);
   for (i = 0 ; i < ARRAY_SIZE ; i++) {
      MyStruct1[i] = MyStruct();
      MyStruct1[i].m_i = i + 40;
   }

   for (i = 0 ; i < ARRAY_SIZE ; i++)
      Console::WriteLine(MyStruct1[i].m_i);
}

Output

下面的示例演示如何执行聚合初始化交错数组。

// mcppv2_array_of_arrays_aggregate_init.cpp
// compile with: /clr
using namespace System;
#define ARRAY_SIZE 2
int size_of_array = 4;
int count = 0;

ref class MyClass {
public:
   int m_i;
};

struct MyNativeClass {
   int m_i;
};

int main() {
   // Declares an array of user-defined reference types
   // and performs an aggregate initialization.
   array< array< MyClass^ >^ >^ MyClass0 = gcnew array<array<MyClass^>^> {
      gcnew array<MyClass^>{ gcnew MyClass(), gcnew MyClass() },
      gcnew array<MyClass^>{ gcnew MyClass(), gcnew MyClass() }
   };

   for ( int i = 0 ; i < ARRAY_SIZE ; i++, size_of_array += 4 )
      for ( int k = 0 ; k < ARRAY_SIZE ; k++ )
         MyClass0[i][k] -> m_i = i;

   for ( int i = 0 ; i < ARRAY_SIZE ; i++ )
      for ( int j = 0 ; j < ARRAY_SIZE ; j++ ) 
         Console::WriteLine("MyClass0[{0}] = {1}", i, MyClass0[i][j] -> m_i);
   Console::WriteLine();

   // Declares an array of value types and performs an aggregate initialization.
   array< array< Int32 >^ >^ IntArray = gcnew array<array< Int32 >^> {
      gcnew array<Int32>{1,2},
      gcnew array<Int32>{3,4,5}
   };

   for each ( array<int>^ outer in IntArray ) {
      Console::Write("["); 

      for each( int i in outer )
         Console::Write(" {0}", i);

      Console::Write(" ]");
      Console::WriteLine();
   }
   Console::WriteLine();

   // Declares and initializes an array of pointers to a native type.
   array<array< MyNativeClass * >^ > ^ MyClass2 = 
      gcnew array<array< MyNativeClass * > ^> {
         gcnew array<MyNativeClass *>{ new MyNativeClass(), new MyNativeClass() },
         gcnew array<MyNativeClass *>{ new MyNativeClass(), new MyNativeClass(), new MyNativeClass() }
      };

   for each ( array<MyNativeClass *> ^ outer in MyClass2 )
      for each( MyNativeClass* i in outer )
         i->m_i = count++;

   for each ( array<MyNativeClass *> ^ outer in MyClass2 ) {
      Console::Write("[");
      for each( MyNativeClass* i in outer )
         Console::Write(" {0}", i->m_i);
      Console::Write(" ]");
      Console::WriteLine();
   }
   Console::WriteLine();


   // Declares and initializes an array of two-dimensional arrays of strings.
   array<array<String ^,2> ^> ^gc3 = gcnew array<array<String ^,2> ^>{ 
      gcnew array<String ^>{ {"a","b"}, {"c", "d"}, {"e","f"} },
      gcnew array<String ^>{ {"g", "h"} } 
   };

   for each ( array<String^, 2> ^ outer in gc3 ){
      Console::Write("[");
      for each( String ^ i in outer )
         Console::Write(" {0}", i);
      Console::Write(" ]");
      Console::WriteLine();
   }
}

Output

托管数组作为模板类型参数

此示例演示如何使用托管数组作为参数传递给模板：

// mcppv2_template_type_params.cpp
// compile with: /clr
using namespace System;
template <class T> 
class TA {
public:
   array<array<T>^>^ f() {
      array<array<T>^>^ larr = gcnew array<array<T>^>(10);
      return larr;
   }
};

int main() {
   int retval = 0;
   TA<array<array<Int32>^>^>* ta1 = new TA<array<array<Int32>^>^>();
   array<array<array<array<Int32>^>^>^>^ larr = ta1->f();
   retval += larr->Length - 10;
   Console::WriteLine("Return Code: {0}", retval);
}

Output

托管数组的 typedef

此示例演示如何使托管数组的 typedef:

// mcppv2_typedef_arrays.cpp
// compile with: /clr
using namespace System;
ref class G {};

typedef array<array<G^>^> jagged_array;

int main() {
   jagged_array ^ MyArr = gcnew jagged_array (10);
}

对数组

不同于标准 C++ 数组，托管数组从其继承常见行为的数组基类隐式派生。示例是 Sort 方法，可用于按所有数组的项目。

对包含基本的内部类型的数组，可以调用 Sort 方法。您可以重写排序条件，因此，需要这样做，如果要为某些复杂类型时排序。在这种情况下，数组元素类型必须实现 IComparable::CompareTo 方法。

// array_sort.cpp
// compile with: /clr
using namespace System;

int main() {
   array<int>^ a = { 5, 4, 1, 3, 2 };
   Array::Sort( a );
   for (int i=0; i < a->Length; i++)
      Console::Write("{0} ", a[i] );
}

如何通过使用自定义标准的数组

若要对包含基本的内部类型的数组，请调用 Array::Sort 方法。但是，对包含复杂类型或重写该默认值排序条件的数组，请重写 IComparable::CompareTo 方法。

在下面的示例中，名为 Element 的结构 IComparable从派生，并编写提供使用平均值两个整数作为排序条件的 CompareTo 方法。

using namespace System;

value struct Element : public IComparable {
   int v1, v2;

   virtual int CompareTo(Object^ obj) {
      Element^ o = dynamic_cast<Element^>(obj);
      if (o) {
         int thisAverage = (v1 + v2) / 2;
         int thatAverage = (o->v1 + o->v2) / 2;
         if (thisAverage < thatAverage)
            return -1;
         else if (thisAverage > thatAverage)
            return 1;
         return 0;
         }
      else
         throw gcnew ArgumentException
      ("Object must be of type 'Element'");
   }
};

int main() {
   array<Element>^ a = gcnew array<Element>(10);
   Random^ r = gcnew Random;

   for (int i=0; i < a->Length; i++) {
      a[i].v1 = r->Next() % 100;
      a[i].v2 = r->Next() % 100;
   }

   Array::Sort( a );
   for (int i=0; i < a->Length; i++) {
      int v1 = a[i].v1;
      int v2 = a[i].v2;
      int v = (v1 + v2) / 2;
      Console::WriteLine("{0}  (({1}+{2})/2) ", v, v1, v2);
   }
}

数组协变

将引用具有直接或间接基类 B 的选件类 D，数组类型 D 可以分配给类型 B. 数组变量。

// clr_array_covariance.cpp
// compile with: /clr
using namespace System;

int main() {
   // String derives from Object.
   array<Object^>^ oa = gcnew array<String^>(20);
}

对数组元素的赋值与数组的动态类型将是为兼容。对于具有不兼容类型的数组元素的一个分配引起 System::ArrayTypeMismatchException 将引发。

数组协变不适用于某些值选件类类型。例如，甚至不使用装箱，数组 Int32 无法转换为数组，System::object^。

// clr_array_covariance2.cpp
// compile with: /clr
using namespace System;

ref struct Base { int i; };
ref struct Derived  : Base {};
ref struct Derived2 : Base {};
ref struct Derived3 : Derived {};
ref struct Other { short s; };

int main() {
   // Derived* d[] = new Derived*[100];
   array<Derived^> ^ d = gcnew array<Derived^>(100);

   // ok by array covariance
   array<Base ^> ^  b = d;

   // invalid
   // b[0] = new Other;

   // error (runtime exception)
   // b[1] = gcnew Derived2;

   // error (runtime exception),
   // must be "at least" a Derived.
   // b[0] = gcnew Base;

   b[1] = gcnew Derived;
   b[0] = gcnew Derived3;
}

请参见

参考

数组（C++ 组件扩展）

通过

如何：在 C++/CLI 中使用数组

一维数组

交错数组

托管数组作为模板类型参数

托管数组的 typedef

对数组

如何通过使用自定义标准的数组

数组协变

请参见

参考

其他资源