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== 14.6#h(0.6em)Chapter summary


  Highlights from this chapter include:


  - Python can read and write data in files using the built-in open() function.
- Due to buffering, changes to a file may not be visible until the file is closed.
- Newline characters need to be removed/added when reading/writing files.
- Comma-separate-value (CSV) files are commonly used to represent data.
- Exceptions that cause a program to terminate can be handled using try and except.
- Raising an exception is an alternative way to return from a function when an error occurs.


  #figure(table(
  columns: 2, align: left, inset: 6pt,
  table.header([Statement], [Description]),
  [file = open("myfile.txt")], [Open a file for reading.],
  [file = open("myfile.txt", 'w')], [Open a file for writing.],
  [file = open("myfile.txt", 'a')], [Open a file for appending.],
  [file.close()], [Close a file after making changes.],
  [data = file.read()], [Read the entire contents of a file. The variable data is a string.],
  [data = file.readline()], [Read the next line of a file. The variable data is a string.],
  [data = file.readlines()], [Read all lines of a file. The variable data is a list of strings.],
  [file.write("Have a nice day!\\n")], [Writes a line to a file. In contrast to print(), the write() function does not automatically append a newline.],
  [file.write(\["Line 1\\n", "Line 2\\n"\])], [Writes multiple lines to a file. As with write(), a newline is not automatically added at the end of each line.],
  [try:
    \# Statements
except:
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  [try:
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    \# Statements
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  [raise ValueError], [Raises a ValueError with no specific error message.],
  [raise ValueError("number is prime")], [Raises a ValueError with the message "number is prime".],
))