Python File IO and Exception Handling
This document covers File I/O Handling and Exception Handling in Python , detailing how to read from and write to files , as well as handle exceptions . It outlines the importance of file operations, different file modes, and standard functions for accessing file contents. Additionally, it explains input and output operations, including reading keyboard input and printing to the screen.
It details exception handling mechanisms such as 'try:except:' statements, various I/O operations including reading input and printing output, and file handling techniques like opening, reading, writing, and closing files in different modes. Additionally, it introduces user-defined exceptions and the syntax for raising exceptions in Python .
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File I/O and Operation A file is a container in computer storage devices used for storing data. When we want to read from or write to a file , we need to open it first. When we are done. It needs to be closed so that the resources that are tied with the file are freed. Hence, in Python , a file operation takes place in the following order: Open a ...
Reasons for using exceptions for file I/O (continued) An exception may occur when opening or reading from the file may occur for many different (some not so clear) reasons: no file with this name, file permissions don't allow access, file is corrupt, device on which the file was stored has been dismounted etc. etc.
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for line in sys.stdin: print line You can also receive command line arguments from sys.argv[ for arg in sys.argv: $ python program.py here are some arguments
In this chapter, you will dive into exceptions , file objects, for loops, and the os and sys modules. If you've used exceptions in another programming language, you can skim the first section to get a sense of Python 's syntax. Be sure to tune in again for file handling .
Lab 6 Exceptions and File IO
Exceptions Every programming language has a formal way of indicating and handling errors. In Python , we raise and handle exceptions . Some of the more common exceptions are listed below, along with the kinds of problems that they typically indicate.
FILE I/O WITH WITH with open("myfile.txt", 'r') as f: for line in f: # do something with line statement automatically closes file
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Managing Files in Python Python provides a simple, elegant interface to storing and retrieving data in files . open : establish a connection to the file and associate a local file handle with a physical file . close : terminate the connection to the file . read : input data from the file into your program. write : output data from your program to ...
File handling refers to the process of performing operations on a file , such as creating, opening, reading, writing and closing it through a programming interface.