beginner level
1. The basic data types
Refer to the link: https://www.cnblogs.com/AntonioSu/p/12273701.html
2. String type
Refer to the link: https://www.cnblogs.com/AntonioSu/p/11957499.html
3. container
Common container: https://www.cnblogs.com/AntonioSu/p/11864333.html
4. Object-Oriented
Package: https://www.cnblogs.com/AntonioSu/p/12269457.html
Inheritance: https://www.cnblogs.com/AntonioSu/p/12269150.html
Polymorphic: https://www.cnblogs.com/AntonioSu/p/12196623.html
Advanced
Memory Allocation: https://www.cnblogs.com/AntonioSu/p/12273116.html
Process of compiling run: https://www.cnblogs.com/AntonioSu/p/12196525.html