Thorough Explanation of C++ Hello World

• Articles about C/C++

• In-depth explanation of Hello World - Qiita

• pre-processing

  • In addition to macro substitution,
  • When a line starting with # ~~~ is encountered, it does various things

    • #include: Searches for a file from the relative path to the file being analyzed or from the include path, and expands it on that line.

    • Is it really just copying the entire contents?

  • The#include directive has two ways to specify the file name: using "" and using <>. Each has different behaviors.

    • The latter goes only to the include path
      • Are there std something in the include directory?
  • Uses of macros
    • include guard
      • Since INCLUDE_GUARD is already defined from the second time onwards, is the code ignored when it is expanded in pre-processing?

• Pointers c

char a = 'a'
char* b = &a
char c = *b // The value of 'a' that the pointer b points to is assigned to c

- > In other words, the notation char* b is equivalent to char *b. In this case, you can also see that "the type of b is char*" in addition to "the type of *b is char".
    - I see~(blu3mo)
- Why `char** argv`?
    - Variables of arrays hold the pointer to the first element
        - So the type of the variable of char array becomes `char*`
    - Is the pointer to that "array" `char**`?
- Don't know the strings of each element in argv
    - So, when reading, read until the end literal `\0` comes

• using namespace std is used to avoid conflicts with other namespaces for std

  • An error occurs if there is a conflict
  • Is this only for C++?

• Integer literals

  • Both unsigned and signed consume the same amount of memory
  • You can indicate the type by adding a suffix after the value

• String literals

  • The ’\0’ added at the end is the null character. In C and C++, strings are often assumed to be null-terminated, so an additional character is added for null termination. It’s a historical reason.