有没有一种方法来初始化与非恒定的数组变量？ （C ++） [英] Is there a way to initialize an array with non-constant variables? (C++)

问题描述

我想创建一个类，例如：

I am trying to create a class as such:

class CLASS
{
public:
    //stuff
private:
    int x, y;
    char array[x][y];
};

当然，这是行不通的，直到我换 INT X，Y; 到

const static int x = 10, y = 10;

这是不现实的，因为我想从文件中读取x和y的值。那么，有没有办法与非contant值初始化数组或声明数组，并在不同的语句声明它的大小？我知道这可能需要一个数组类的创作，但我不知道从哪里开始就这一点，我并不想创建一个二维动态列表时，数组本身不是动态的，只是大小在编译时不知道的。

Which is impractical, because I am trying to read the values of x and y from a file. So is there any way to initialize an array with non-contant values, or declare an array and declare its size on different statements? And I know this would probably require the creation of an array class, but I'm not sure where to start on this, and I don't want to create a 2D dynamic list when the array itself is not dynamic, just the size is not known at compile-time.

推荐答案

编译器需要有一流的确切大小编译时，你将不得不使用new操作符来动态分配内存。

The compiler need to have the exact size of the class when compiling, you will have to use the new operator to dynamically allocate memory.

切换字符数组[X] [Y]为char **数组;和初始化在构造函数中的数组，并且不要忘记删除数组在析构函数。

Switch char array[x][y]; to char** array; and initialize your array in the constructor, and don't forget to delete your array in the destructor.

class MyClass
{
public:
    MyClass() {
        x = 10; //read from file
        y = 10; //read from file
        allocate(x, y);
    }

    MyClass( const MyClass& otherClass ) {
        x = otherClass.x;
        y = otherClass.y;
        allocate(x, y);

        // This can be replace by a memcopy
        for( int i=0 ; i<x ; ++i )
            for( int j=0 ; j<x ; ++j )
                array[i][j] = otherClass.array[i][j];
    }

    ~MyClass(){
        deleteMe();
    }

    void allocate( int x, int y){
        array = new char*[x];
        for( int i = 0; i < y; i++ )
            array[i] = new char[y];
    }

    void deleteMe(){
        for (int i = 0; i < y; i++)
           delete[] array[i];
        delete[] array;
    }

    MyClass& operator= (const MyClass& otherClass)
    {
        if( this != &otherClass )
        {
            deleteMe();
            x = otherClass.x;
            y = otherClass.y;
            allocate(x, y);
            for( int i=0 ; i<x ; ++i )
                for( int j=0 ; j<y ; ++j )
                    array[i][j] = otherClass.array[i][j];            
        }
        return *this;
    }
private:
    int x, y;
    char** array;
};

*编辑：
我已经拷贝构造函数
并赋值运算符

* I've had the copy constructor and the assignment operator

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