如何初始化这个可变大小的结构？ 我如何初始化下面声明的可变大小C++结构体结构：< /p> #include <iostream> #include <string> typedef struct { char* a; int b; } StructA; typedef struct { StructA* pointers[]; int pcount; int numbers[]; int ncount; } StructB; int main() { StructB *sb = new StructB; // I need 'sb' to be allocated in the heap sb->pcount = 5; sb->ncount = 3; sb->pointers = new StructA*[sb->pcount]; sb->numbers = int[sb->ncount]; } 听，这不是好的C++方式，你在C++环境下做C 这是好的，如果它给你一些优势IO，打字检查等或学习。 C风格的动态内存分配完全是手动的。解除分配也是如此。 由于您使用的是typedef，typedef可以让您和编译器更清楚地了解情况。 这是一个折磨人的例子，我想这正是你想要的。 请注意，这是一种艰难的方式，在这种情况下，这实际上是一种简单的方式 C++中的C风格编码；p> #include <iostream> #include <string> typedef struct { char* a; int b; } StructA; typedef StructA* A_p; // A_p is "pointer to structA" (contains address of struct) typedef A_p* A_p_Array; // A_p_Array is "pointer to A_p" (aka StructA**) contains address of A_p typedef int* int_Array; // int_Array is "pointer to int" contains address of integer typedef struct { A_p_Array A_pointers; int pcount; int_Array numbers; int ncount; } StructB; int main() { int i; StructA *sa = new StructA; StructB *sb = new StructB; sb->pcount = 5; sb->ncount = 3; A_p_Array tmp_A_array; A_p tmp; for ( i = 0 ; i < sb->pcount; i++) { tmp_A_array = new A_p; // create a StructA pointer tmp = new StructA; // create a StructA tmp_A_array = &tmp; // put address of tmp in mp_A_array tmp_A_array++; // increment array address } sb->A_pointers = tmp_A_array; // A_pointers now contains address of dynamically created array tmp_A_array = NULL; // clear pointer but do NOT delete! int_Array tmp_i_array; for ( i = 0 ; i < sb->ncount; i++) { tmp_i_array = new int(0); // c++ can create ints with initial values tmp_i_array++; } sb->numbers = tmp_i_array; tmp_i_array = NULL; // clear pointer but do NOT delete! /****** USE Structs A & B *****/ // clean up the heap A_p Ap; for ( i = 0 ; i < sb->pcount; i++) { Ap = sb->A_pointers[i]; delete Ap; // each struct released separately } int* ip; for ( i = 0 ; i < sb->ncount; i++) { ip = & sb->numbers[i]; delete ip; //each int released separately } delete sb; return 0; } // main

有更好的方法来实现上述目标 这就是C++和高级语言的一个原因。 当你开始上课的时候，会比较容易 但是你也会遇到同样的问题 所以，把指针和指针放下来

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现在，以后会对你有好处。

你的代码不是有效的C++，标准C++不支持VLA。据我所知，int数[]；在C++中不允许作为结构成员。它在C中是允许的，但只能作为最后一个成员——换句话说，int-ncount；紧接着也使其成为非法C。只需使其成为StructA**指针；和int*number；。或者，更好的是，使用向量，因为这是C++而不是C.@ CDHOWIE：不，数组不是指针。不过数组会退化为指针。@EduardoLeón我不确定这在所有情况下都是正确的-例如，我非常确定void fooint x[]等同于void fooint*x。

#include <iostream>
#include <string>


typedef struct {
char* a;
int b;
} StructA;


typedef StructA* A_p;   // A_p is "pointer to structA" (contains address of struct)                                                                           

typedef A_p* A_p_Array; // A_p_Array is "pointer to A_p"  (aka StructA**) contains address of A_p                                                             

typedef int* int_Array; // int_Array is "pointer to int" contains address of integer                                                                          


typedef struct {
 A_p_Array A_pointers;
 int pcount;
 int_Array numbers;
 int ncount;
} StructB;


int main()
{
 int i;

 StructA *sa = new StructA;

 StructB *sb = new StructB;

 sb->pcount = 5;
 sb->ncount = 3;

 A_p_Array  tmp_A_array;
 A_p        tmp;

 for ( i = 0 ; i < sb->pcount; i++)
 {
  tmp_A_array = new A_p; // create a StructA pointer                                                                                                      
  tmp = new StructA;     // create a StructA                                                                                                              
  tmp_A_array = &tmp;    // put address of tmp in mp_A_array                                                                                              
  tmp_A_array++;         // increment array address                                                                                                       
 }


 sb->A_pointers = tmp_A_array; // A_pointers now contains address of dynamically created array                                                               

 tmp_A_array = NULL;  // clear pointer but do NOT delete!                                                                                                    

 int_Array tmp_i_array;
 for ( i = 0 ; i < sb->ncount; i++)
 {
  tmp_i_array = new int(0); // c++ can create ints with initial values                                                                                    
  tmp_i_array++;
 }

 sb->numbers = tmp_i_array;
 tmp_i_array = NULL;  // clear pointer but do NOT delete!                                                                                                    


 /****** USE  Structs A & B    *****/

 // clean up the heap                                                                                                                                        

 A_p Ap;

 for ( i = 0 ; i < sb->pcount; i++)
 {
  Ap =  sb->A_pointers[i];
  delete Ap;  // each struct released separately
 }

 int* ip;
 for ( i = 0 ; i < sb->ncount; i++)
 {
  ip = & sb->numbers[i];
  delete ip;  //each int released separately
 }

 delete sb;

  return 0;
} // main