The first type of file we are going to read from is a simple text file with multiple lines of text. To do that, let’s first create a text file with the following lines.
Learn Python in One Day and Learn It Well
Python for Beginners with Hands-on Project
The only book you need to start coding in Python immediately
http://www.learncodingfast.com/python
Save this text file as myfile.txt to your desktop. Next, fire up IDLE and type the code below. Save this code as fileOperation.py to your desktop too.
f = open (‘myfile.txt’, 'r')
firstline = f.readline()
secondline = f.readline()
print (firstline)
print (secondline)
f.close()
The first line in the code opens the file. Before we can read from any file, we have to open it (just like you need to open this ebook on your kindle device or app to read it). The open() function does that and requires two parameters:
The first parameter is the path to the file. If you did not save fileOperation.py and myfile.txt in the same folder (desktop in this case), you need to replace ‘myfile.txt’ with the actual path where you stored the text file. For instance, if you stored it in a folder named ‘PythonFiles’ in your C drive, you have to write ‘C:\\PythonFiles\\myfile.txt’ (with double backslash \\).
The second parameter is the mode. This specifies how the file will be used. The commonly used modes are
'r' mode:
For reading only.
'w' mode:
For writing only.
If the specified file does not exist, it will be created.
If the specified file exists, any existing data on the file will be erased.
'a' mode:
For appending.
If the specified file does not exist, it will be created.
If the specified file exist, any data written to the file is automatically added to the end
'r+' mode:
For both reading and writing.
After opening the file, the next statement firstline = f.readline() reads the first line in the file and assigns it to the variable firstline.
Each time the readline() function is called, it reads a new line from the file. In our program, readline() was called twice. Hence the first two lines will be read. When you run the program, you’ll get the output:
Learn Python in One Day and Learn It Well
Python for Beginners with Hands-on Project
You’ll notice that a line break is inserted after each line. This is because the readline() function adds the ‘\n’ characters to the end of each line. If you do not want the extra line between each line of text, you can do print(firstline, end = ‘’). This will remove the ‘\n’ characters. After reading and printing the first two lines, the last sentence f.close() closes the file. You should always close the file once you finish reading it to free up any system resources.