Learn C language with Peng brother

1. Learned what C language is and wrote the first C language program
2. Learned the data types of C language, know why there are so many types and the size of each type
3. Learned how to define variables, variables are divided into local variables and global variables
4. Learned the use of variables

5. Also understand the scope and life cycle of variables

                                                                     2021.1.12