c++ - 在对象中创建对象数组时的默认构造函数

Question

我正在尝试在另一个对象中创建对象数组(特别是 Checkbook 中的 Check 数组。我不允许使用 vector 代替动态数组来存储对象，这让人抓狂，但那些是已经规定给我的规则。

我遇到的问题是我需要为 check 构造函数提供几个变量，因为它需要在 check 中构造一个 Money 对象 对象。 所以我收到一条错误消息，声称 Check* checkArray = new Check[]; 没有默认构造函数。

此后我添加了一个默认构造函数，它只是 Check::Check() {};，但是我如何动态填充数组而不在创建时将参数最初传递给构造函数？我是 OOP 的新手，正在努力管理类(class)内的类(class)。 注意:money 类是预定义和实现的

这些相关支票的数据以 int(check number) '\t' double(check amount) '\t' int(bool for cashed in 0 or 1) 和我暂时将数据存储在 struct DataTransferStruct 中，然后将结构存储在 vector 中只是为了测试，但我无法在最终实现中使用该 vector 。我处理这个问题的方式不好吗？

相关代码如下:

class Money
{
    private:
        long all_cents;

    public:
        friend Money operator +(const Money& amount1, const Money& amount2); //Returns sum of the values of amount1 and amount2
        friend Money operator -(const Money& amount1, const Money& amount2); //Returns amount1 minus amount2
        friend Money operator -(const Money& amount); //Returns the negative of the value of amount
        friend bool operator ==(const Money& amount1, const Money& amount2); //Returns true if amount1 and amount2 have the same value; false otherwise
        friend bool operator <(const Money& amount1, const Money& amount2) { return (amount1.all_cents < amount2.all_cents); }; //Returns true if amount1 is less than amount2; false otherwise

        Money(long dollars, int cents); // Initializes the object so its value represents an amount with the dollars and cents given by arguments.  If the amount is 
        //negative, then both dollars and cents should be negative

        Money::Money(long dollars) : all_cents(dollars * 100) {} //Initializes the object so its value represents $dollars.00

        Money::Money() : all_cents(0) {}//Initializes the object so its value represnets $0.00

        double get_value() const; //Returns the amount of money recorded in the data portion of hte calling object
};

检查类

class Check
{
    //Check dataTypes
    private:
        int checkNum;
        Money checkAmount;
        bool cashed;

    public:
        //Constructor
        Check::Check(long dollar_Value, int cents_Value, int check_Num, int cashed_) : checkAmount(CreateMoneyClass(dollar_Value, cents_Value)) { checkNum = check_Num; if (cashed_ == 1)cashed = true; else cashed = false; };
        Check::Check() {};
        //Deconstructor
        Check::~Check() {};

        //Member functions
        Money CreateMoneyClass(long dollar_Value, int cents_Value);
        int GetCheckNum() const { return checkNum; };
        double GetCheckAmount() const { return checkAmount.get_value(); };
        bool CheckCashed() const { return cashed; };

};

Money Check::CreateMoneyClass(long dollar_Value, int cents_Value)
{
    //Function that creates a Money object and returns to checkAmount within Check class 
    Money temp(dollar_Value,cents_Value);

    return temp;
}

刚刚上CheckBook课

class CheckBook
{
    //Checkbook contains an array of checks
    private:
        Check* checkArray = new Check[];

};

我用来存储信息的方法

NewFile_Open(newFile);

    //take in and format each data line w/ struct and then construct check in dynamic growing array
    while (newFile >> temp.checkID)
    {
        newFile >> temp.rawMoneyAmount;
        newFile >> temp.checkCashed;

        //set dollars = rawMoneyAmount which drops cents
        temp.dollars = temp.rawMoneyAmount;

        //Get cents as int
        temp.cents = (int)((temp.rawMoneyAmount - temp.dollars) * 100);
    }

Answer 1

你不应该在类里面创建这样的数组

class CheckBook
{
    //Checkbook contains an array of checks
    private:
        Check* checkArray = new Check[];

};

您应该在类 CheckBook 构造函数中定义它。

喜欢

class CheckBook
    {
        //Checkbook contains an array of checks
        private:
            Check* checkArray;
        Checkbook()
        {
         checkArray = new checkArray[size];
        }
    };