Ruby学習#27 Writing Files

Jim, Sales
Andy, Sales
Kelly, Customer Service
Creed, Quality Assurance
Michaes, Manager

stack overflow Questions Ruby IO

mode meaning

r read-only
w write-only, truncates existing file to zero length or creates a new file for writing
a write-only, starts at end of file if file exists, otherwise creates a new file for reading and writing

File.open("employees.txt", "a") do |file|
file.write("\nOscar, Accounting")
end

Jim, Sales
Andy, Sales
Kelly, Customer Service
Creed, Quality Assurance
Michaes, Manager
Oscar, Accounting

File.open("employees.txt", "w") do |file|
file.write("\nOscar, Accounting")
end

Oscar, Accounting

File.open("index.html", "w") do |file|
file.write("

Hello

")
end

index.html にHello Worldできてる。

from stackoverflow
r+ Read-write, starts at beginning of file.

File.open("index.html", "r+") do |file|
file.readline()
file.write("Hi")
end

Jim, Sales
Hidy, Sales
Kelly, Customer Service
Creed, Quality Assurance
Michaes, Manager
Oscar, Accounting

File.open("index.html", "r+") do |file|
file.readchar()
file.write("Hi")
end