{"id":12192,"date":"2020-12-14T11:43:44","date_gmt":"2020-12-14T19:43:44","guid":{"rendered":"https:\/\/careerkarma.com\/blog\/?p=12192"},"modified":"2023-12-01T04:05:54","modified_gmt":"2023-12-01T12:05:54","slug":"do-while-python","status":"publish","type":"post","link":"https:\/\/careerkarma.com\/blog\/do-while-python\/","title":{"rendered":"Do While Python: A Step-By-Step Guide"},"content":{"rendered":"\n

The do while Python loop executes a block of code repeatedly while a boolean condition remains true. The Python syntax for while loops is while[condition]. A “do while” loop is called a while loop in Python.<\/em><\/p>\n\n\n\n

Most programming languages include a useful feature to help you automate repetitive tasks. This feature is referred to as loops<\/em>.<\/p>\n\n\n\n

For example, say you want to write a program that prints out individually the names of every student in a list. You may want to use a loop to print out each name rather than separate print() statements.<\/p>\n\n\n\n

In this tutorial, we are going to break down the do while loop<\/em> (which is officially called a while loop<\/em>) in Python. A while loop can be used to repeat a certain block of code based on the result of a boolean condition. The code in the while block will be run as long as the statement in the while loop is True.<\/p>\n\n\n\n

We\u2019ll also run through a couple of examples of how to use a do while<\/em> loop in Python.<\/p>\n\n\n\n

For Loop Refresher<\/h2>\n\n\n\n

Loops are useful in a vast number of different situations when you\u2019re programming. As a result, Python has two built-in functions that allow you to create loops: for and while.<\/p>\n\n\n\n

Here\u2019s an example of a Python for loop<\/a> in action that iterates through a range of values:<\/p>\n\n\n\n

for i in range(0, 3):\n\tprint(i)<\/pre><\/div>\n\n\n\n
We use a Python range() statement<\/a> to create a list of values over which our while loop can iterate. Our code returns:<\/p>\n\n\n\n
0\n1\n2<\/pre><\/div>\n\n\n\n
The for loop sets i<\/em> as the iterator, which keeps track of how many times the loop has been executed. The loop runs three times, or once for each item in the range of 1 and 3<\/em>.<\/p>\n\n\n\n
Do While Python<\/h2>\n\n\n\n
Python do while loops run a block of code while a statement evaluates to true. The loop stops running when a statement evaluates to false. A  condition evaluates to False at some point otherwise your loop will execute forever.<\/p>\n\n\n\n
Here\u2019s the syntax for creating a while loop in Python:<\/p>\n\n\n\n
while [our condition is True]:\n\t[run code]<\/pre><\/div>\n\n\n\n
We use the “while” keyword to denote our while loop.<\/p>\n\n\n\n
Our loop will continue to run until the condition being evaluated is equal to false. In many programming languages, this is called a do while<\/em> loop, but in Python we simply refer to it as a while loop<\/em>.<\/p>\n\n\n\n
Once our condition evaluates to False, the loop is terminated. A loop that does not have a condition that evaluates to False is called an infinite loop. This type of loop is called an infinite loop because it does not run for a specified number of times. The loop keeps going.<\/p>\n\n\n\n
Each time the while loop runs, our code checks the condition in the loop. If the condition is met, the loop is run.<\/p>\n\n\n\n
This is slightly different to a “do while” loop with which you may be familiar in other programming languages. A “do while” loop executes a loop and then evaluates a condition. “do while” loops do not exist in Python so we’ll focus on regular while loops.<\/p>\n\n\n\n
Let\u2019s use an example to illustrate how a while loop works in Python.<\/p>\n\n\n\n
Python Do While Example<\/h2>\n\n\n\n
We are going to create a program that asks a user to guess the magic number. Our program should continue to run until the user guesses correctly.<\/p>\n\n\n\n
If the user guesses the number incorrectly, the loop will keep going, and if the user guesses the correct number, the loop will stop.<\/p>\n\n\n\n
Write a Basic While Loop<\/h3>\n\n\n\n
Here\u2019s the code for our example while<\/em> loop program that runs whlile a condition is True:<\/p>\n\n\n\n
user_guess = 0\nmagic_number = 5\n\nwhile user_guess != magic_number:\n\tprint('What is the magic number?')\n\tuser_guess = int(input())\n\nprint('You have correctly guessed the magic number!')<\/pre><\/div>\n\n\n\n
On the first two lines of our code, we declare two Python variables<\/a>. The user_guess<\/em> variable will be used to store the number our user inputs into the program. The magic_number<\/em> variable stores the number the user is attempting to guess.<\/p>\n\n\n\n
On the next line, we declare our while<\/em> loop. This loop checks if the variable user_guess<\/em> is not equal to magic_number<\/em>, and if these values are not the same, the loop will run. In other words, if our user has not guessed the correct magic number, the while loop will execute. The code inside our while loop is called the body of the loop.<\/p>\n\n\n\n
We print the statement “What is the magic number?”<\/em> We then use the Python input()<\/em> function<\/a> to request a guess from the user.<\/p>\n\n\n\n
Our program will check to see if the while<\/em> condition is still True when the user presses the enter key. When the condition becomes False, our loop stops executing.<\/p>\n\n\n\n
Testing the Program<\/h3>\n\n\n\n
Here\u2019s what happens if we guess the wrong number:<\/p>\n\n\n\n
What is the magic number?\n1\nWhat is the magic number?\n2\nWhat is the magic number?\n3\nWhat is the magic number?<\/pre><\/div>\n\n\n\n
If we guess the wrong number, the program executes the while<\/em> loop again. Our loop keep running until we enter the right number. At this point, our loop body will stop running and our program will move on.<\/p>\n\n\n\n
Here\u2019s what happens if we guess the correct number:<\/p>\n\n\n\n
What is the magic number?\n5\nYou have correctly guessed the magic number!<\/pre><\/div>\n\n\n\n
After we guessed the correct number, user_guess<\/em> was equal to magic_number<\/em> and so our while loop stopped running. Then, our program printed out the message stating that we had correctly guessed the magic number.<\/p>\n\n\n\n
Remember that when you\u2019re working with input()<\/em>, you may need to convert the values that you are receiving from a user. In our case, we had to use int(input())<\/em> because we were gathering numbers from a user. If we wanted our values to be strings, though, we would not have to convert our values.<\/p>\n\n\n\n
Improving the Do While Python Loop Example<\/h2>\n\n\n\n
Now that we know the basics of while loops in Python, we can start to explore more advanced loops. We are going to create another guessing game. But, this time we are going to include a few additional features to make it more functional for users.<\/p>\n\n\n\n
The specifications for our program are as follows:<\/p>\n\n\n\n