# 開發工具和規格標準 [筆記]
contributed by < `happyincent` >

* [講座共筆](https://hackmd.io/s/HJFyt37Mx#)
* [直播錄影](https://www.youtube.com/watch?v=scLFY2CRtFo)
---

* C++
* 這個世紀的 C++ 為 meta language (object programming , generic programming, ...)
* 改版飛快，內建許多功能，編譯器不相容問題
* gcc 和 g++ 一樣嗎?
* 發現自己電腦上 (WSL, Windows Subsystem for Linux) gcc -v 和 g++ -v 的內容差不多

            $ diff <(gcc -v 2>&1) <(g++ -v 2>&1)
            2c2
            < COLLECT_GCC=gcc
            ---
            > COLLECT_GCC=g++

* [ [ source ] ](https://stackoverflow.com/questions/172587/what-is-the-difference-between-g-and-gcc)
* 兩者都屬於 GNU Compiler Collection
* `g++` is equivalent to `gcc -xc++ -lstdc++ -shared-libgcc`
:::info
gcc 是 compiler driver，參見 [編譯器和最佳化原理篇](https://hackmd.io/s/Hy72937Me)
:notes: jserv
:::

* musl-libc
* glibc 是 LGPL (例外條款等授權問題)，musl-libc 是 MIT (最寬鬆，只需留下作者名字)
* 改 Alpine Linux 的 Dockerfile 時看到 musl 相關的 package
* 發現 Alpine Linux 預設就是使用 musl-libc

* designated initializer

    struct point p = { .y = yvalue, .x = xvalue };
    // is equivalent to
    struct point p = { xvalue, yvalue };

* C++ 不支援 (C++ 有 constructor)
* C 更注重具體的執行順序

* 第一個 C 語言的編譯器
* 組語寫只有基本 C 功能的 C0 (the bootstrap compiler)，C0 -> C1, C1 -> C2 ...
* bootstraping: producing a self-compiling compiler [(wiki)](https://en.wikipedia.org/wiki/Bootstrapping_(compilers))
* e.g. PyPy

* [ISO/IEC 9899](http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf)
* null 念作 null 不是 怒偶
* `*` 念作 asterisk，`**` 念作 pointer to pointer
* `&` address-of operator

        int a[] = { 1, 2, 3 };
    
        if ( (void *)a == (void *)&a ) {
            printf("%p\n",  a    );  // 0x7ffff5cb1430
            printf("%p\n",  a + 1);  // 0x7ffff5cb1434
            printf("%p\n", &a + 1);  // 0x7ffff5cb143c
        }

* sizeof (operator)
* incomplete types (types that describe objects but lack information needed to determine their sizes)
* 6.2.5 - 20
* e.g.

            struct A;
            struct A *a;
            sizeof(struct A); // incomplete
            sizeof(&a);       // 8, 64-bit

* cdecl `declare 英文 -> C` `explain C -> 英文`
* gdb
* [DWARF](http://wiki.dwarfstd.org/index.php?title=DWARF_FAQ#What_is_DWARF.3F) (debugging data format, 矮人), ELF (Executable and Linkable Format, 精靈)
* [gdb-peda](https://github.com/longld/peda)
* Python Exploit Development Assistance for GDB
* colorize
* Application checkpointing
* save state
* e.g. crash (memory, resource, user-kernel inconsistent)

* x/nfu `<address>`: Print memory [[GDB cheat sheet](https://darkdust.net/files/GDB%20Cheat%20Sheet.pdf)]
* n: How many units to print (default 1)
* f: Format character
* a Pointer
* c Read as integer, print as character
* **d Integer**, signed decimal
* f Floating point number
* **o Integer**, print as octal
* s Try to treat as C string
* **t Integer**, print as binary (t = "two")
* u Integer, unsigned decimal
* **x Integer**, print as hexadecimal
* u: Unit
* b: Byte
* h: Half-word (2 bytes)
* w: Word (4 bytes)
* g: Giant word (8 bytes)

* vscode (git, debugger)
* [Install on Linux](https://code.visualstudio.com/docs/setup/linux)