Class One

Intro

• Buzzword

  encapsulation 封装 inheritance 继承
  polymorphism 多态
  overriding 覆盖
  interface 接口
  cohesion 内聚
  coupling 耦合
  collection classes 容器类
  template 模板
  responsibility-driven design 责任驱动设计

• Book reference: Thinking in C++

• The C language

  Efficient programs
  direct access to machine
  flexible

• C++ improvements

  data abstraction
  access control
  initialization & cleanup
  function overloading
  stream for I/O

• The first program
  

      #include <iostream>  
      using namespace std;  
      int main()  
      {
          cout << "Hello, World!"<< endl;  
  
      }  
  

• iostream is a header file name without a .h suffix. iostream.h happens to exist, yet it is an outdated version
• <<: inserter
• cin >> variable: extractor
• use ; to connnect the shell commands

Format output

• #include <iomanip>: manipulators are special functions that can be included in the I/O statement to alter the format parameters of a stream.
• endl is one of them
• setw(int width): set the output width
• setprecision(int n): set the number of digits in decimal parts

String

• #include <string>: c don't have a string type
• string str: a string
• str="Hello" , str("Hello"), s3{"see see"} for every type, yet when it comes to the third way of initialization, one should add g++ -std=c++11 when compiling.
• objects can transfer contents through =
• cin: only read the first word
• getline(cin, str): read the whole line
• string s[0]: the first character of the string, the same as the array in c
• string s2=string s1+ string s3: string concatenation
• s2.length(): the length of the string
• s2(s3,2,3): the third to the fifth character of s3, 2 is the starting position, 3 is the length of the substring
• s2.substr(2,3): the same as above
• insert(size_t pos, const string& str): insert a string into another string
• erase(size_t pos, size_t len): erase a substring
• replace(size_t pos, size_t len, const string& str): replace a substring with another string
• find(const string& str, size_t pos=0): find the first occurrence of a substring
• append(const string& str): append a string to another string
• string *p=&s: a pointer to a string
• s->length(): the length of the string, the same as (*s).length()
• string s1, s2; s1=s2;: copy the string, two different objects
• string *p=&s1; string *q=&s2; p=q;: two pointers point to the same object s2