Bo2SS

Programming with vim#

• Save file and exit: , ZZ
• In Linux, everything is a file
  • Executable program a.out is also a file, a binary file
• .cpp files can contain C code, but not vice versa (C++ code in .c files)
  • Note: Some macros under C11 standard are not compatible with C++

C programming conventions#

• Mainstream coding conventions in China: ali + google, baidu + google. Refer to Google C++ Style Guide
• PS:
  • Leave a blank line between two functions: one empty line is enough
  • Generally use CamelCase naming convention: MyName (capitalized), myName (lowercase)

How to debug a program#

• Common sense: The program defaults to using main() function as the entry point
• Function encapsulation: After defining a function, have you called it?
• When encountering compilation errors: Find the error from top to bottom, debug
• When the result is unexpected: Try using printf to output the value of variables

How to use and improve programming skills with HZOJ#

• Start with HZOJ-Entry Group
• Small exercise👇

HZOJ-69: Start of School Exam 2: Date Judgment#

Sample Input

1991 1 30
1991 1 32

Sample Output

Yes
No

• Approach
  • Check for invalid input, check if the number of days in a month is reasonable (leap year)
  • Two versions
    • Complex if-else statements: heavily nested
    • Trade space for time: create an array of days in each month
• Code
  • 
  • Version 1
    • The key lies in the use of arrays
    • The ternary operator is not a conditional statement, so there is no branch prediction issue
  • Version 2
    • Low readability
    • Complex logic, prone to bugs
    • Consider branch prediction issue - preloading process, low efficiency
      • Refer to 《C Language and Enhancement》- 3 Program Flow Control Methods - CPU Branch Prediction

Reflections on prime number problems#

• Cryptography is related to prime numbers
• See 《C Language and Enhancement》- 5.Arrays and Preprocessing Commands - Prime Sieve, Linear Sieve and Code Demonstration sections