CP104 Lecture Notes - Lecture 8: Gnu Readline, For Loop
17 May 2018
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- First step: open file
- E.g file_handle(whatever name)=open(filename,mode,encoding)
- USE OPEN
- file_handle=’
- close() to close file at the end data may be lost if not closed
- By default it reads
- For loop for files is like a list of strings
- Eg. for line in myfile:
- 1) open the file
- 2) process the file
- 3) close the file
- mode=’r’
- ‘W’ write in file
- ‘A’ cursor at the end file
- \n at the end of lines of string there counts as a number (file processing SLIDE)
- \n counts as one letter, not 2
- For line in myfile:--->deals as list of strings
- readline() method advances cursor to where we are reading
- Read line till ‘\n’
- To count words: how many words or letters? For loop
READING WHOLE FILE AS A SINGLE STRING
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- readlines()
- User for loop and handle
Have to convert to string when writing in a file
- e.g myfile.write(str(4))
Can't do two for loops because the cursor is at the bottom after first for loop:
-instead put it i a list
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Document Summary
Use open file_handle=" close() to close file at the end data may be lost if not closed. For loop for files is like a list of strings. Eg. for line in myfile: open the file, process the file, close the file. \n at the end of lines of string there counts as a number (file processing slide) For line in myfile:--->deals as list of strings. Read line till \n" readline() method advances cursor to where we are reading. Reading whole file as a single string readlines() Have to convert to string when writing in a file e. g myfile. write(str(4)) Can"t do two for loops because the cursor is at the bottom after first for loop: When an existing file is opened, the w" mode erases the contents of the file. When opening the file with append the cursor is located at the end of the file. Prints backlash so if 6 lines 12 will be printed.
