Computer Science Programming Basics in Ruby

11.2 File Access: Reading and Writing

To access files, the built-in Ruby File class is used. This class contains multiple methods. We use the following: open, close, gets, and puts. The method File.open instantiates a new object that enables Ruby to read from or write to an existing or new file. The object returned by File.open can then be used by Ruby to access the file. The following code shows how to open a file:

myfile = File.open(file_name, access_mode)

The myfile variable is a File object that can now be used to interact with the file’s contents, depending on what access mode is used. Note that file name and access mode are strings. The variable file_name is a representation of a path to a file, such as /home/ruby/file.txt. The myfile variable in our program is local to only our program. Two of the most basic access modes and what they do are shown in Table 11-1.

Table 11-1. Some file access modes

Mode	Description
r	Read access only. Points to start of the file. This is the default, but it is good programming style to specify it anyway.
w	Write access only. Points to the beginning of the file that will overwrite the file’s content if it already exists.

Gem of Wisdom

Files provide access to data resident in the computer system’s long-term memory. Storage in long-term memory, such as disks, provides data resiliency, namely, permanence. That is, disks work even without power, so they store things far longer than the internal random access memory, which works only if the ...