Files and Streams

First Line

Reading the first line is a common stream operation.

first record The first logical line is often a title, header, or command before later data.

First Line

raw
first_line.lua
Replay: real traced execution (multi-file project)
local raw = "title|body"
local text = string.gsub(raw, "|", "\n")
local first = string.match(text, "^[^\n]+")

print("raw=" .. raw)
print("first=" .. first)

local raw = "header|detail"
local text = string.gsub(raw, "|", "\n")
local first = string.match(text, "^[^\n]+")

print("raw=" .. raw)
print("first=" .. first)

local raw = "single"
local text = string.gsub(raw, "|", "\n")
local first = string.match(text, "^[^\n]+")

print("raw=" .. raw)
print("first=" .. first)

  1. raw ← title|body, text ← title body, first ← title

    1local raw→ title|body = "title|body" --@raw="header|detail", "single"2local text→ title
body = string.gsub(rawtitle|body, "|", "\n")3local first→ title = string.match(texttitle
body, "^[^\n]+")45print("raw=" .. rawtitle|body)6print("first=" .. firsttitle)
    outputraw=title|body
first=title

  1. raw ← header|detail, text ← header detail, first ← header

    1local raw→ header|detail = "header|detail"2local text→ header
detail = string.gsub(rawheader|detail, "|", "\n")3local first→ header = string.match(textheader
detail, "^[^\n]+")45print("raw=" .. rawheader|detail)6print("first=" .. firstheader)
    outputraw=header|detail
first=header

  1. raw ← single, text ← single, first ← single

    1local raw→ single = "single"2local text→ single = string.gsub(rawsingle, "|", "\n")3local first→ single = string.match(textsingle, "^[^\n]+")45print("raw=" .. rawsingle)6print("first=" .. firstsingle)
    outputraw=single
first=single