C-CPP-Programming-in-case-of

Data Structure Alignment 数据结构对齐 #

x86-64 architecture #

Overall rule: any data structure/element should be accessed by CPU with minimum CPU cycles. A 32bit CPU can access 4Bytes in one cycle, while a 64bit one can access 8Bytes. When a memory access is not aligned, it is said to be misaligned (wiki).
Thus, there are two practical rules for us to understand compiler’s padding:

Rule 1: any basic data structure/element/variable should be aligned so that their beginning address is divisible (任何变量的开始地址都能被自己的大小整除，即：当被访问的数据长度为 n 字节时，数据地址为 n 字节对齐。).

C,CPP Programming & Variable Naming Rules

File Ambiguity #

file: can be only filename, or full/relative path + filename.
location: full/relative path + filename.
filename: only name part, no path in string.
path: full/relative path w/o filename.

Common & Suggested Usages #

//Common   → Suggested
chars      → charSize
bytes      → byteSize
int  * buf → int  *p_intListing
char * buf → char *p_inputFile
ifstream in→ ifstream inputStream

IF Statement Evaluation #

if (c) is: if(c != 0)
if (!c) is : if (c == 0)
similar for boolean vars:
false === 0 and true === !0 === !false
However, all true evaluates to int 1: