![]() # Check and retrieve command-line arguments #!/usr/bin/env python3 # -*- coding: UTF-8 -*- """įile_copy: Copy file line-by-line from source to destination The following script copies a file into another line-by-line, prepending each line with the line number. The with-statement is equivalent to the try-finally statement as follows:į.close() Example: Line-by-line File Copy Line = line.strip() # Strip the leading/trailing whitespaces and newline # Process the line # File closed automatically upon exit of with-statement With open('path/to/file.txt', 'r') as f: # Open file for read We can use a with-statement to open a file, which will be closed automatically upon exit, and a for-loop to read line-by-line as follows: > f.close() Processing Text File Line-by-Line Line = line.rstrip() # strip trailing spaces and newline # process the line print(line) line = f.readline() > f.close() # Read line-by-line using readline() in a while-loop > f.read() # Read entire file into a string > f.close() # Open the file for reading and read the entire file via read() > f.readline() # Return an empty string after EOF > f.readlines() # Read all (next) lines into a list of strings > f.readline() # Read next line into a string > f.close() # Always close the file # Check the contents of the file created # Open the file created for reading and read line(s) using readline() and readlines() The '\n' will be translated to the platform-dependent newline ( '\r\n' for Windows or '\n' for Unixes/Mac OS).Įxamples # Open a file for writing and insert some records You need to explicitly terminate the str with a '\n', if needed. fileObj.write( str) -> int: Write the given string to the file and return the number of characters written.fileObj.read() -> str: Read the entire file into a string.fileObj.readlines() -> : Read all lines into a list of strings.It returns an empty string after the end-of-file (EOF). fileObj.readline() -> str: (most commonly-used) Read next line (upto and include newline) and return a string (including newline). ![]() It initially positions at the beginning of the file and advances whenever read/write operations are performed. The fileObj returned after the file is opened maintains a file pointer.
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