1. No const constructor
Unlike other member functions, constructors may not be declared as const . When we create a const object of a class type, the object does not assume its “constness” until after the constructor completes the object’s initialization. Thus, constructors can write to const objects during their construction
2. Synthesized default constructor
The compiler-generated compiler is known as synthesized default constructor
For most classes, the synthesized default constructor initializes each data member as follows: if there is an in-class initializer, use it to initialize the member; otherwise, default initialize the member.
3.Why sometimes should difine default constructor for classes?
A reason to define default constructor is that for some classes, the synthesized default constructor does the wrong thing. The objects of built-in or compound type(such as array and pointer) that are defined inside a block have undefined value when they are default initialized. Therefore, classes that have members of built-in or compound type should either be initialized inside the class or define their own version of default constructor.
Another reason that some classes must define their own default constructor is that sometimes the compiler is unable to synthesize one. For example, if a class has a member of a class type, and that class doesn't have a default constructor , then the compiler can't initializer that member.
P.S. Classes that have members of built-in or compound type rely on synthesized default constructor only if all such members have in-class initializer.
4. Constructor initializer list
Constructor initializer list specifies initial values for one or more data members of the object being created.
5. Difference of default access level between class and struct
The default access specifier in strcut is public whereas that in class is private.
P.S. The only difference using class and using strcut to define a class is the default access level.
6. friend class or function
A class can allow other class or function to access its non-public members by making the class or function a friend.
P.S. Friend declaration should be inside a class definition and they may be anywhere in the class. Friends are not members of the class and aren't affected by the access specifier.
7. Benefits of encapsulation
1) User code can't inadvertently corrupt the state of an encapsyulated object
2) The user-level code doesn't need change when the implementation of can encapsulated class changes.
8. Friend class
The member functions of a friend class can access all the members, including non-public members of the class granting friendship.
P.S. Classes and non-member functions need not have been declared before they are used in a friend declaration.
9. What's name lookup?
Name lookup is the process of which declaration matches the use of a name.
10. Name lookup process
First look for a declaration of a name in the block where the name is used. Only name declared before is considered. Then if the name isn't found, look in the enclosing scope(s). If no declaration is found, then the program is in error.
11. Class definition are processed in two phases:
First, the member declarations are compiled. Function bodies are compiled only after the entire class has been seen.
12. Normal block-scope name lookup inside member functions
A name used in a body of member function is resolved as follows:
First, look for the declaration of the name inside the function body. As usual, only declarations in the part preceding the use of the name should be considered.
Then if no declaration is found inside the member function, look up declarations inside class. All the members of the class should be considered.
If no declaration is found inside the class, look for declarations in the scope that before the member function definition.
13. Constructor initializers are sometimes required(constructor initializer vs. assignment in constructor)
Members that are const or reference must be initialized. Similarly, members of a class type that doesn't have a default constructor must be initialized.
14. Order of member initialization
Members are initialized in the order that they appear in the class definition. The order in which the initializer appears in the constructor initializer list doesn't change the order of initialization.
P.S. It's a good idea write constructor initializer in the same order as the members are declared. Moreover, when possible, avoid using members to initialize other members.
15. Constructor and default arguments
A constructor that supplies default arguments for all its parameters also defines the default constructor.
16. Delegating constructor(C++11 feature)
A delegating constructor use another constructor from its class to perform its initialization.
17. We must initialize the static data member outside the class body.
18. Static data members vs. ordinary data members
1) Static data members can have incomplete data type. In particular, a static data member can have the same type as the class of which it is a member. A non-static member is restricted to a pointer or reference.
2) We can use a static member as a default argument.
随机推荐
-
NSURLConnection学习笔记
虽说现在都用三方库来获取网络数据,再不济也会用苹果官方的NSURLSession,但有些东西还是要先学会才有资格说不好不用,不是么? NSURLConnection发送请求是分为同步和异步两种方式的, ...
-
排名前 8 的 PHP 调试工具
Web 开发并不是一项轻松的任务,有超级多服务端脚本语言提供给开发者,但是当前 PHP 因为具有额外的一些强大的功能而越来越流行.PHP 是最强大的服务端脚本语言之一,同时也是 web 开发者和设计者 ...
-
Edit Distance
Edit Distance Given two words word1 and word2, find the minimum number of steps required to convert ...
-
C#委托之泛型
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Cons ...
-
C++例题1：输出可打印字符
#include<iostream>#include<stdlib.h>#include<cctype>int main(){ int i;char a=0; fo ...
-
HDU 2553 N皇后问题（详细题解）
这是一道深搜题目!问题的关键是在剪枝. 下面我们对问题进行分析: 1.一行只能放一个皇后,所以我们一旦确定此处可以放皇后,那么该行就只能放一个皇后,下面的就不要再搜了. 2.每一列只能放一个皇后,所以 ...
-
2016年9月3日 文成小盆友python-num18 － django进阶一
一.深入django的路由系统 下面为django的请求生命周期 下面来看下整个生命周期中的路由系统: 在Django的urls中我们可以根据一个URL对应一个函数名来定义路由规则如下: " ...
-
git添加比较和合并工具(meld)
git 下的(difftool)和(mergetool)是专门提供给使用者用自己的工具进行diff和merge的命令: # git config --global diff.tool meld # g ...
-
BZOJ_1801_[Ahoi2009]chess 中国象棋_DP
BZOJ_1801_[Ahoi2009]chess 中国象棋_DP Description 在N行M列的棋盘上,放若干个炮可以是0个,使得没有任何一个炮可以攻击另一个炮. 请问有多少种放置方法,中国像 ...
-
用Java实现给图片添加文字
package image; import java.awt.Color; import java.awt.Font; import java.awt.Graphics2D; import java. ...