Bo2SS

Writing Programs with Vim#

• Save and exit: , ZZ
• In Linux, everything is a file
  • The executable program a.out is essentially a file, a binary file
• You can write C code in .cpp files, but not the other way around (writing C++ code in .c files)
  • Note: Some macros under the C11 standard are not compatible with C++

C Language Programming Standards#

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

How to Debug Programs#

• Common knowledge: The program defaults to main() as the entry point
• Function encapsulation: After defining a function, has it been called?
• When compilation errors occur: Look for errors from top to bottom, debug
• If it does not meet expectations: Try using printf to output variable values

Using Pirate OJ and Improving Programming Skills#

• First, practice on HZOJ-Introductory Group
• Small exercises 👇

HZOJ-69: School Opening Exam 2: Date Judgment#

Sample Input

1991 1 30
1991 1 32

Sample Output

Yes
No

• Idea
  • Check for illegal input and whether the number of days in the month is reasonable (leap year)
  • Two versions
    • Complex if-else judgment: wildly nested
    • Space for time: create an array of days in the month
• Code
  • 
  • Version one
    • The key lies in the use of arrays
    • The ternary operator is not a conditional statement, so there will be no branch prediction issues
  • Version two
    • Low readability
    • Complex logic, prone to bugs
    • Consider branch prediction issues - preloading process, low efficiency
      • Refer to “C Language and Improvement” - 3 Program Flow Control Methods - CPU Branch Prediction

Thoughts on Prime Number Problems#

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