(concat , append) This keeps original data and adds new text after it.

String Method `format!`, `+`, `push_str`, `push`, `concat`, `join`

default 사용법 & 반복적이고 귀찮은 default를 꼭 만들자

rust Standard Library(std) training

std rust arrays map, free function

array와 Vec를 메모리를 찍어보며 구성을 예측해보자

I’ll explain Array vs Vec memory layout, where data lives, what’s on stack vs heap, and why performance differs, using clear CLI diagrams you can see with your eyes.

shift training