Week 3: Session 1

File I/O and the Operating System

The computer's file system is made up of files and directories. Directories may contain files. Files contain data.

Activity 1: Review Week 2

• Decision making
• Logical Operators and Expressions
• Looping

Activity 2: Demostrate where file I/O is used in the Game.

Activity 3: What is I/O? Input/Output

Review Console I/O

str = input("Input your favorite color? ")
print ("Outputting your favorite color: ",str)

First, Create a file by Writing to It

What does "#write" mean?

#write
myfile = open("myfile","w")
myfile.write("hello")
myfile.close()
print (myfile.name, "is open?", myfile.closed)

Next, Read the file and write its contents to the console

#read
myfile = open("myfile","r")
str = myfile.read()
print ("contents of ",myfile.name,": ",str)
myfile.close()

Exercise

Create a text file in the IDE (manually without code).

Write a program that read the data from the file and writes the output to the console.

Write a program that asks the user a question and then writes the answer to a file.

Write a program that reads the file and prints the output to the console.

What happens if you run the read file program before the write file program?

Activity 4: What is "os"? Operating System

Test that a file exists

print("this file exists?",os.path.isfile("file-exists.py") )

Renaming a file

What is the import command doing? What is "os"?

import os
os.rename( "myfile.txt", "test.txt" )

Removing a file

import os
os.remove("test.txt")

Working with Directories and Calling Programs from Code

Make a directory and then go to it to make a file. What does "../" mean?

import os

os.mkdir("test")
os.chdir("test")
os.system("python ../file-write.py")

Activity 5: Create a challenge that uses a file

Create a file with a question.

Read the file to get a question that you ask for the challenge.