C++类中声明二维数组并在构造函数初始化的技术问题

Alright, let's break down the issues with your code and fix them properly. You're hitting two core C++ rules here when dealing with member arrays in a class:

1. The Problem with Your Current Code #

First, let's call out the key mistakes:

• Invalid array declaration: In C++, you can't declare a 2D array like int map[][] — you must specify the size of all dimensions except possibly the first. The compiler needs clear dimensions to calculate memory allocation and array indexing.
• Illegal array assignment: You can't directly assign an initializer list like { {...}, {...} } to an array after it's been declared (which happens when the TForm1 instance is created). Raw arrays don't support this kind of assignment syntax.

2. Solution 1: Fixed-Size 2D Array #

If you know the exact dimensions of your map upfront (let's assume 15 columns, matching your first row of 15 elements, and 10 rows for example), here's how to fix it:

Step 1: Update the Header File #

Declare the array with explicit dimensions:

class TForm1 : public TForm {
private:
    // ... your other private members ...
public:
    __fastcall TForm1(TComponent* Owner);
    // Specify fixed dimensions: [number_of_rows][number_of_columns]
    int map[10][15]; 
};

Step 2: Initialize in the Constructor #

Since direct assignment isn't allowed, use one of these approaches:

Option A: Loop to Copy Values

__fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) {
    // Define your initial map data
    int initialMap[10][15] = {
        {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
        {1,2,0,0,0,0,0,0,0,0,0,0,0,0,1},
        // Add the rest of your rows here
        {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
    };

    // Copy each element to the member array
    for (int i = 0; i < 10; ++i) {
        for (int j = 0; j < 15; ++j) {
            map[i][j] = initialMap[i][j];
        }
    }
}

Option B: Use std::copy (C++11+)

For a more concise approach:

#include <algorithm> // Required for std::copy

__fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) {
    int initialMap[10][15] = {
        {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
        {1,2,0,0,0,0,0,0,0,0,0,0,0,0,1},
        // Rest of the rows...
    };

    for (int i = 0; i < 10; ++i) {
        std::copy(std::begin(initialMap[i]), std::end(initialMap[i]), std::begin(map[i]));
    }
}

3. Solution 2: Use std::vector<std::vector<int>> (Flexible Size) #

If your map size might change later, or you want simpler initialization, use a nested vector instead of a raw array. This is the more modern, flexible approach:

Step 1: Update the Header File #

#include <vector> // Add this include at the top of your header

class TForm1 : public TForm {
private:
    // ... your other private members ...
public:
    __fastcall TForm1(TComponent* Owner);
    std::vector<std::vector<int>> map; 
};

Step 2: Initialize in the Constructor #

Now you can directly assign the initializer list with no extra hoops:

__fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) {
    // Initialize the vector with your map data directly
    map = {
        {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
        {1,2,0,0,0,0,0,0,0,0,0,0,0,0,1},
        // Add all your rows here
        {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
    };
}

This approach avoids raw array limitations and makes resizing or modifying the map later much easier.

内容的提问来源于stack exchange，提问作者Samy Dressel