We generally use this loop when we don't know the number of times to iterate beforehand. Please use ide.geeksforgeeks.org, The next block prints the result. To start, here is the structure of a while loop in Python: In the next section, you’ll see how to apply this structure in practice. Example #4: Iteration over particular set of element. Code language: Python (python) How it works. The while loop is used to execute a block of code until the specified condition becomes False. In many real-life examples, you need to check multiple conditions. Experience. The loop iterates while the condition is true. And so, in this case, the condition will be: Putting everything together, the Python code would look like this: Let’s now see how to use a ‘break’ statement to get the same result as in example 3: Run the code and you’ll indeed get the same results as in the third example: How to Create While Loop in Python (with 4 Examples), The value of the countdown will decrease by intervals of 1. ; Python for loop is always used with the “in” operator. While loops let the program control to iterate over a block of code. But, in addition to the standard execution of statements in a loop, you can skip the execution of statement(s) in while loop for this iteration, using builtin Python continue statement.. 2018-06-10T21:14:48+05:30 Python, strings No Comment In this article we will discuss different ways to iterate or loop over all the characters of string in forward, backward direction and also by … Using Extended Slice. This repeats until the condition becomes false. return i + 1 i = 0 # Use a while-True loop on one line. In python, while loop repeatedly executes the statements in the loop if the condition is true. ; Third, show the value of the counter variable and increase it by one in each iteration. The program first evaluates the while loop condition. While Loop. This is less like the for keyword in other programming languages, and works more like an iterator method as found in other object-orientated programming languages.. With the for loop we can execute a set of statements, once for each item in a list, tuple, set etc. code, Example #3: Iterate characters in reverse order. while test_expression: Body of while Perform iteration over string_name by passing particular string index values. string = "the crazy programmer" print "original = " + string string = string[::-1] … Python doesn’t provide a feature of a Do-While loop, But if you wanna use it in python, then you can create a program using a Do-While loop. The while loop has its use cases. Syntax of while Loop in Python while test_expression: Body of while You will learn following loops in python: for loop; while loop; nested loop; for loop. Here is the full Python code to perform the while loop for our example: Once you run the code, you’ll get the following countdown: Sometimes you may want to use a ‘break’ statement to end the loop when a specific condition is met. And when the condition becomes false, the line immediately after the loop in the program is executed. You can use for loop on strings, lists, multiple numbers as they are collection of items. If the user enters an empty string, the T (True) block is executed: a break statement so the while block exits. Syntax of While Loop in Python: while test_expression: body of while. You will also learn how to use nested loops in python. acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Important differences between Python 2.x and Python 3.x with examples, Statement, Indentation and Comment in Python, How to assign values to variables in Python and other languages, Python | NLP analysis of Restaurant reviews, Adding new column to existing DataFrame in Pandas, Count numbers < = N whose difference with the count of primes upto them is > = K, Leftmost and rightmost indices of the maximum and the minimum element of an array, Python program to convert a list to string, How to get column names in Pandas dataframe, Reading and Writing to text files in Python, Python | Split string into list of characters, Python program to check whether a number is Prime or not, Write Interview close, link While Loop In Python A while statement iterates a block of code until the controlling expression evaluates to True. A while loop statement in Python programming language repeatedly executes a target statement as long as a given condition is true. Writing code in comment? As the condition is never going to be False, the control never comes out of the loop, and forms an Infinite Loop as shown in the above diagram. Introducing while Loops. Flowchart – Python Infinite While Loop Following is the flowchart of infinite while loop in Python. Its construct consists of a block of code and a condition. Example – Python Infinite While Loop with True for Condition Python Basics — 3: If Statements, User Input, While Loop Content. How to iterate over an Array using for loop in Golang? Try it Yourself ». How to iterate through a nested List in Python? If the user entered a string, the block continues with calling the function "stringTotal (userinput)", assigning the returned value to the variable name "total". A while loop runs as long as a certain condition is True.The while loops syntax looks like this:. for loop in Python language. Let’s have a look at the syntax. Using for loop. Python program that uses while, one-line functions. How to iterate over a JavaScript object ? By using our site, you Data Structures and Algorithms – Self Paced Course, We use cookies to ensure you have the best browsing experience on our website. In other words, we need a loop, and the most simple looping mechanism in Python is the while loop. The general syntax of a Python for loop looks like this: . In a while loop, the test condition is checked first and if it is true then the block of statements inside the loop is executed. As others loops, while loops in python allow programmers to set certain portions of their code to repeat through a number of loops which are referred to as iterations. You have to use the below-given example to print all the items of the list element. a = 0 while a < 10: a = a + 1 print a In this program, we’ll ask for the user to input a password. You can loop through string variable in Python with for loop or while loop. Similar post. The following flowchart explains the working of while loop in Python. While loop falls under the category of indefinite iteration. You have to use the print statement to print each letter one by one. Python programming language provides following types of loops to handle looping requirements. If so, I’ll show how to create this type of loop using 4 simple examples. The following are various ways to iterate the chars in a Python string.Let’s first begin with the for loop method. For the user to input a password can do multiple operations on it has two loop control –... Code within the block is executed isn ’ t specified explicitly in advance and true is any non-zero.. 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