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c++的良好习惯_爱写代码的小白程序员的技术博客_51CTO博客
source link: https://blog.51cto.com/u_15059356/5638219
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c++的良好习惯
精选 原创对象的初始化
1.使用对象前需要确保对象已经初始化
初始化和赋值
class PhoneNumber
{
};
class ABEntry
{
public:
ABEntry(std::string name, std::string address, std::list<PhoneNumber>& phone, int num);
private:
std::string mName;
std::string mAddress;
std::list<PhoneNumber> mPhones;
int mNumTimeConsulted;
};
// 赋值
ABEntry::ABEntry(std::string name, std::string address, std::list<PhoneNumber>& phone, int num)
{
mName = name;
mAddress = address;
mPhones = phone;
mNumTimeConsulted = num;
}
{
};
class ABEntry
{
public:
ABEntry(std::string name, std::string address, std::list<PhoneNumber>& phone, int num);
private:
std::string mName;
std::string mAddress;
std::list<PhoneNumber> mPhones;
int mNumTimeConsulted;
};
// 赋值
ABEntry::ABEntry(std::string name, std::string address, std::list<PhoneNumber>& phone, int num)
{
mName = name;
mAddress = address;
mPhones = phone;
mNumTimeConsulted = num;
}
以上操作都是进行赋值操作，而不是初始化，这样能够带来你想要的成员变量的值，但是C++有更好的办法
初始化发生的阶段比较早，一般是在进入构造函数本地之前，所以更好的做法就是使用初始化模板
ABEntry::ABEntry(std::string name, std::string address, std::list<PhoneNumber>& phone, int num)
: mName(name),mAddress(address),mPhones(phone),mNumTimeConsulted(num)
{
}
: mName(name),mAddress(address),mPhones(phone),mNumTimeConsulted(num)
{
}
这种做法的结果和上面的赋值操作是相同，但是相率更高，赋值操作需要调用进入构造函数本体里面进行操作，刚好初始化模板就避免了这个问题
2.构造析构和赋值
每一个所写的类都有一个或者多个默认构造函数，析构函数，copy assignment操作符
为了避免编译器为我们自动生成一些不是期待的相关函数，应该直接定义相关函数，拒绝编译器自动生成相关的函数
不要在构造函数和析构函数调用virtual相关的函数
class Transaction
{
public:
Transaction();
virtual void logTransaction() const = 0;
};
class BuyTransaction : public Transaction
{
public:
virtual void logTransaction() const;
};
class SellTransaction : public Transaction
{
public:
virtual void logTransaction() const;
};
Transaction::Transaction()
{
logTransaction();
}
BuyTransaction b; // 会发生什么？
{
public:
Transaction();
virtual void logTransaction() const = 0;
};
class BuyTransaction : public Transaction
{
public:
virtual void logTransaction() const;
};
class SellTransaction : public Transaction
{
public:
virtual void logTransaction() const;
};
Transaction::Transaction()
{
logTransaction();
}
BuyTransaction b; // 会发生什么？
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