notes

Link to Notion Notes: https://www.notion.so/Ethereum-II-11-18-2019-8107efa574234d0cab1eb74e4afc0b9a

Arrays
Two sizings: compile-time or STATIC sized arrays AND
Dynamic arrays
Basic Syntax
 T[k]. T is type - e.g., uint, String, even array or
struct. k is size - num of elements
 ^^^ is fixed-size array

 T[ ] uint[]. <—dynamic array holding type uint
 uint corresponds to Z+0
 Int correspond to Z
 uint[5]

 uint[][5]. = [[], [], …]
 If T is an array, T[k] is always an array containing k
elements of type T
 Arrays in Solidity are zero indexed
 To declare an array, the full syntax is:

 T[k] arrName
Sp’ uint[][5] x memory
Access the 2nd uint in the 3rd dynamic array. ——> x[2][1]
Accessing an array past its end causes a failing assertion
.push() method appends a new element to the end of a
DYNAMIC STORAGE ARRAY. ***NB The method returns
new length of the array
.pop() method - DYNAMIC STORAGE ARRAYS - remove
element from end of array
MEMORY ARRAYS CANNOT BE RESIZED!!!!
Notes:
 Increasing the length of a storage array has constant gas
costs because storage is assumed to be zero initialized.
 Decreasing the length of a storage array has at least
linear (often worst) gas costs, because it includes explicitly 
clearing the removed elements similar to calling :ref:delete