Python tutorial 21: Python Print To File by Manish Sharma

Key Takeaways

let's start from where we left off last week today I will show you how to permanently redirect the output stream to file in Python programming I will try to keep it short and easy to understand like always let's do it what's up Internet I am manish from rebellionrider.com where we make learning computer programming form as mentioned earlier in this tutorial I will show you a hassle-free process of how to save the output of all the Python print statements into a file but first please consider subscribing to add notified whenever I upload information pack the Python programming tutorials that make learning form now let's start right in front of you is the code which we wrote last week the problem with it is that the output of only those print statements is getting saved permanently into a file where file parameter has been used for example in this code the output of the first print statement will get saved into the file whereas the output of the second print statement will get displayed back to the user on the computer screen this is all because of the file parameter which we have used in the first print statement but not in the second one now suppose I have a Python program which has ten print statements I want to save the output returned by all these print statements into a file on my operating system now the question here is do I need to use the file parameter with all of them or is there an alternative way of doing that well there is nothing wrong in doing that but in case if you don't want to then you can go the old-school way let's learn what is that first let's create a new worksheet for today's tutorial for that let's go to our project directory Python tutorials which we created last week here we are let's name this file duty 21 dot py now let's open it I will be using atom editor you can use whatever editor or IDE you want here we go now let's write some code here we have the first part of the program in the first line I am importing this module this is an inbuilt module of python libraries in the second statement I am redirecting the default output stream to a file this is a very important statement so let me explain it to you as you can see it's an assignment statement on the left hand side of the assignment operator we have sis not STD out STD out here is a file object if not set to anything then by default it sends the output to the default output stream which is almost always the screen of your system but we can reset it and that is what we are doing in this statement now let us come to the right-hand side of the assignment operator on the right hand side we have the Python open function we already know that this function returns a file object of the file whose name we have specified into it as a result on execution of this statement the interpreter will reset the default behavior of the STD out from printing the output on the screen to saving it into a file which you have is specified into the Python open function you will understand it when I will complete this code so let's write a print statement now as you can see in this Python print function call I have not specified the file parameter which means the output returned by this function should be displayed to us on the screen this is its usual behavior let's execute and see what happens but before that let me tell you this code has a problem to find out what is that keep watching now let's execute the code execution done but where is the output output is not on the screen because in the second statement we change the default output stream from printing the output on the screen to saving it into the file which means our output should be saved into the file tu t20 underscore output dot txt let's check for that I need to go into my current project directory which is Python tutorials where I created this Python file in the starting of the video here i am here i have the tu t20 underscore output dot txt file let's open it and check if it has our output saved into it or not here is our output now the question here is what if we have more than one print statements will the output of all those statements also get saved into the file let's write a few more print statements to find out the answer now we have total four Python print function calls here I have not used a file parameter in any of these calls now let's execute and see if their outputs also get saved into the file execution done let's check the file tud twenty underscore output dot txt here is our output can you guess why the string from the first Python print statement got printed twice yeah comment yes if you know the answer otherwise check out the comment section I will leave the explanation there so that's how we redirect the output stream from displaying the result on the screen to saving it into a file not to mention this redirection is permanent now let's talk about the problem with this code which I mentioned earlier before I come to that I just want to remind you to check out the corresponding block of this tutorial for detail knowledge that being said let's come to the topic now suppose you added one more print statement to your program and you don't want to save that into the file rather you want to display it back to the user let's add that Python print function call first this print statement is no different than the rest of the others hence on execution the output of this Python print statement will also get saved into the file which we don't want so what options do we have for that I know most of you will suggest saving sis not STD out into sis not STD out like this looks legit let's execute and see if it works or not execution is successful but the output from our last statement is still not on our screen which means the string and of the program must be saved into the file right let's check here is the file let's see if the output from our last Python print statement is saved into it or not and here is a string from our last Python print statement which we don't want now the question here is if saving sis not STD out into sister STD out is not the solution than what to restore the default state of the standard output stream you need to follow a process that process is to save the default state which is sis not STD out into a variable and then assigning it to the standard output stream let me show you how let's create a variable and named it restore point make sure that you must create this variable before the statement which contains the Python open function call which in our case is the second statement now let's save the default state into this variable next we have to assign this variable into sustad STD out that's all you have to do to restore the default behavior of the standard output stream let's execute and see if we are getting the output in the desired format or not the output from all the first four Python print statements are saved into the file but the output of the last print statement is here on the screen which shows that we have successfully restored the standard output stream to its default behavior that is how we work with default output stream in Python if you have watched all the three tutorials of Python print statement then congratulations you have mastered it if you still have any problem feel free to leave a comment down below you can also send me a message on facebook which is facebook.com slash the rebellion right now that's it for today thanks for watching this is Manish from rebellion right calm