Python Programming: Lesson 19 - File I/O смотреть онлайн

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In the previous lesson (https://youtu.be/thm423sR7Uc), we learned about how to handle exceptions. Here, we learn about how to read and write from a text file!

1. Create "sampleText.txt" with some text
file = open( "sampleText.txt" , "r" )
x = file.read( )
print( x ) # reads whatever text currently exists in the text file sampleText.txr
file.close( )
file = open( "sampleText.txt" , "w" ) # w REPLACES the text, rather than appending the text onto what was there
file.write( "sup" ) sends sup to the text file sampleText.txt
file.close( )
file = open( "sampleText.txt" , "r" )
print( file.read( ) ) # sup
file.close( )
file = open( "sampleText.txt" , "a" )
file.write( "not a blank slate" )
file.close( )
file = open( "sampleText.txt" , "r" )
print( file.read( ) ) # sup on one line, then not a blank slate on the next
file.close( )

The readlines( ) method when called on file = open( "sampleText.txt" , "r" ) returns a list, where each element is a line of text that was in sampleText.txt

0:15 Review of Handling Exceptions with try/except
1:26 NEW: Intro to File I/O
1:57 NEW: Creating a Text File for File I/O in Python
3:59 NEW: Reading a File, file = open( "myFile.txt" , "r" )
8:23 NEW: Closing a File when Transitioning Actions, file.close( )
9:30 NEW: Appending Text to the End of a File, file = open( "myFile.txt" , "a" )
13:00 NEW: Writing/Rewriting a Text File, file = open( "myFile.txt" , "w' )
15:07 NEW: The readlines( ) method called on open( "myFile.txt" , "r" ) returns a list, where each line is an element
17:51 NEW: Iterating through the Lines of a Text File with a Loop

An equivalent Java lesson is available here: https://youtu.be/FdRM8IVrbPU

In the next lesson, we will discuss tuples and the None data type: https://youtu.be/48v7LL6XR0A

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