将函数的返回值设置为数组的大小 [英] Setting a return value from a function as the size of an array

问题描述

我有一个返回整数的函数.我将该值存储在变量"count"
中
我想定义一个新的char数组，其大小是此返回值.
例如char new_array[count][20]

列宽20是恒定的.这表示最大字符串长度.

但是当我这样做并尝试编译程序时，它给了我错误:

Hi,

I have a function that returns an integer. I store that value in a variable "count"

I want to define a new char array whose size is this return value.
e.g. char new_array[count][20]

The column width 20 is constant. This represents the max string length.

But when I do this and try to compile the program it gives me the error:

error C2057: expected constant expression

我该怎么做?

How can I do this?

推荐答案

您不能使用变量值声明数组，因为编译器必须在编译时知道数组大小.

您要做的是使用指针创建一个动态数组，如下所示:

Hi,

you can''t declare an array with a variable value, because the compiler has to know the array size at compilation time.

What you have to do is to use a pointer to create a dynamic array like this:

main()
{
   int count = 0;
   int *DynArray = NULL;

   count = GetArraySizeFunction();
   DynArray = new int[count];
   if( NULL != DynArray)
   {
      for( int i0 = 0; count > i0; ++i0)
      {
         DynArray[i0] = 0;
      }

      // do with the array whatever you want

      delete[] DynArray; //Rajesh: Replaced delete with delete[]
                         //Carlo: Replaced ''Replacedd'' with ''Replaced''  :-\
                         //Armin: Replaced ''Replacced'' with ''Replacedd'' in Carlos comment ;-)
   }
}

如果您使用的是C ++，那么使用std::vector<int>之类的东西会更好.

向量，列表，队列等都具有良好的性能和可靠性，并且易于使用！

If you''re using C++, then you''d be far better using something like std::vector<int>.

Vectors, lists, queues, etc., provide both good performance and reliability, and they''re easy to use!

唯一的方法就是使用指针.

int * myArray = new int [count];

我的语法可能不对，我已经好几年没有使用C ++了，但是核心概念绝对正确-创建动态数组的唯一方法是使用指针.您的另一选择是使用动态容器，例如std :: vector.

The only way to do this is with pointers.

int * myArray = new int[count];

My syntax may be off, I''ve not done C++ for years, but the core concept is definitely right - the only way to create a dynamic array is with pointers. Your other option is to use dynamic containers like std::vector.

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