Overview
The key function for working with files in Python is the open() function, which takes two parameters: filename, and mode.
There are four different methods (modes) for opening a file:
- “r” – Read – Opens a file for reading; returns an error if the file does not already exist (default value)
- “a” – Append – Opens a file for appending; creates the file if it does not already exist
- “w” – Write – Opens a file for writing; creates the file if it does not already exist
- “x” – Create – Creates the specified file; returns an error a file with the same name already exists
Additionally, it can be specified whether the file should be handled as binary or text mode.
- “t” – Text – Text mode (default value)
- “b” – Binary – Binary mode (e.g. images)
Either of the following will open the file myfile.txt.
f = open("myfile.txt")f = open("myfile.txt", "rt")Note
Since “r” for read, and “t” for text are the default values, they technically do not need to be specified.
Python Notes:
- The most recent major version of Python is Python 3; however, Python 2 is still in use and quite popular, although not being updated with anything other than security updates
- Python uses new lines to complete a command, as opposed to other programming languages which often use semicolons or parentheses
- Python relies on indentation, using whitespace to define scope, such as the scope of loops, functions, and classes; other programming languages often use curly-brackets for this purpose
- Python string methods return new values, and DO NOT change the original string
- Python tuples are unchangeable after created (their items CANNOT be changed or re-ordered at a later point)
- Python sets are unordered (may appear in random orders when called), unchangeable (the value of individual items cannot be changed after creation), unindexed (items cannot be referred to by index or key), and duplicates are NOT ALLOWED
- As of v3.7, Python dictionaries are ordered and duplicates ARE ALLOWED; in v3.6 and earlier, dictionaries were unordered (did not have a defined order and could not be referred to using an index)
- Python does not have built-in support for arrays, but Python lists can be used as pseudo “arrays”; therefore, all Python list methods will work with these pseudo “arrays”
We’d like to acknowledge that we learned a great deal of our coding from W3Schools and TutorialsPoint, borrowing heavily from their teaching process and excellent code examples. We highly recommend both sites to deepen your experience, and further your coding journey. We’re just hitting the basics here at 1SMARTchicken.