Reading a File Line by Line in Python

Question

I am pretty new to Python. So I was trying out my first basic piece of code. So i was trying to read a file and print it line by line in Python. Here is my code:

class ReadFile(object):

    def main (self):

        readFile = ReadFile()
        readFile.printData()

    def printData(self):

        filename = "H:\\Desktop\\TheFile.txt"

        try:
            with open(filename, 'r') as f:
                value = f.readline()
                print(value)

            f.close()

        except Exception as ex:
            print(ex)

Now When I run it, I get no output. So I tried debugging it. I see the control jumps from one method to another (main --> printData) and then exists. Its doesn't execute anything within the method. Can you tell me what am I doing wrong here? I am new, so a little insight as to why the code is behaving this way would be nice as well.

Answer 1

If the idea here is to understand how to read a file line by line then all you need to do is:

with open(filename, 'r') as f:
  for line in f:
    print(line)

It's not typical to put this in a try-except block.

Coming back to your original code there are several mistakes there which I'm assuming stem from a lack of understanding of how classes are defined/work in python.

The way you've written that code suggests you perhaps come from a Java background. I highly recommend doing one of the myriad free and really good online python courses offered on Coursera, or EdX.

---

Anyways, here's how I would do it using a class:

class ReadFile:
    def __init__(self, path):
        self.path = path

    def print_data(self):
        with open(self.path, 'r') as f:
            for line in f:
                print(line)

if __name__ == "__main__":
    reader = ReadFile("H:\\Desktop\\TheFile.txt")
    reader.print_data()

Answer 2

You don't really need a class for this and neither do you need a try block or a file.close when using a context manager (With open ....).

Please read up on how classes are used in python. A function will do for this

def read():

    filename = "C:\\Users\\file.txt"
       with open(filename, 'r') as f:
          for line in f:
             print(line)