file_io.py

# Example 1: Writing to a .txt file
my_list = [i ** 2 for i in range(1, 11)]
# Generates a list of squares of the numbers 1 - 10

f = open("output.txt", "w")

for item in my_list:
  f.write(str(item) + "\n")

f.close()

# Example 2: Reading a file
my_file = open("output.txt", "r")

print my_file.read()
my_file.close()

# Example 3: Reading line by line
my_file = open("text.txt", "r")
 
print my_file.readline()
print my_file.readline()
print my_file.readline()
my_file.close()

# Example 4: Using With/As statement to avoid closing the file
"""
You may not know this, but file objects contain a special pair of built-in 
methods: __enter__() and __exit__(). The details aren’t important, but what is 
important is that when a file object’s __exit__() method is invoked, it 
automatically closes the file. How do we invoke this method? With with and as.
"""
with open("text.txt", "w") as textfile:
  textfile.write("Success!")

# Example 5: Verifying if file is closed
with open("text.txt", "w") as my_file:
  my_file.write("Success!")

if not my_file.closed:
  my_file.close()

print my_file.closed