Working with files

To work with files, we need the IOStream type. IOStream is a type with the supertype IO and has the following characteristics:

• The fields are given by names(IOStream)

  4-element Array{Symbol,1}:  :handle   :ios    :name   :mark

• The types are given by IOStream.types

  (Ptr{None}, Array{Uint8,1}, String, Int64)

The file handle is a pointer of the type Ptr, which is a reference to the file object.

Opening and reading a line-oriented file with the name example.dat is very easy:

// code in Chapter 8\io.jl
fname = "example.dat"                                 
f1 = open(fname)

fname is a string that contains the path to the file, using escaping of special characters with \ when necessary; for example, in Windows, when the file is in the test folder on the D: drive, this would become d:\\test\\example.dat. The f1 variable is now an IOStream(<file example.dat>) object.

To read all lines one after the other in an array, use data = readlines(f1), which returns 3-element Array...