dataType

理解C++中引用的底层实现s # Type Safety in Programming Languages # Statically v. dynamically v. strongly v. weakly typed languages # Elixir in the Type System Quadrant

# Typing: dynamic vs. static and weak vs. strong—Programming fundamentals

what

b = 100

1. value Type: store Direct value; a = b; a ddress-> [100]

2. reference Type: store Indirect value: address, offset…; a = b; a address-> [b address]

question:

1. reference type vs pointer type; reference type have many forms;reference type = {pointer Type, reference type}

   1. pointer type(): unconst pointr

   1	var q = &a;

   2. reference type(hidden pointer):

   1	let b = {a:1}

2. pointer address and dereference;

   1. address(取址): &a, get variable address;
   2. derefernece: visit variable address *a;

c++ reference type

1. code

   1 2 3

   int i=5; int &ri=i; ri=8

   1 2 3

   int i = 5; int const *ri = &i; *ri=8

2. reference vs pointer

   1. reference is const pointer;
   2. reference Auto addressed and dereferencing;

how

type safety

type check:

1. the variables match the expected type, if not throw error or ingore
2. using the right ingredient when cooking

static/ dymamic : compile time/static time check type

dymanic type

1. can change type
2. don’t need declare the type

weak/strong type: 多大程度实施它的type system

weak: 淡化 type system, 允许implicit conversion strong: 遵循type system, 不允许implicit conversion, throw type error if not saftish the operaiton;

1. 不符合类型的操作 throw type error

strong type = type safety

type error exmaple:

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4

a = "k"
a/2 

TypeError: unsupported operand type(s) for /: 'str' and 'int

why type safety is important: avoid unexpected result (bug)

why c is weak type: allow implicit conversation

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int x = 10; char c = 'a'; // Implicit conversion of char to 
int int result = x + c

type safety data foramt:

在通信的不同进程中，数据的类型是一致的，与schema定义类型一样