The while loop is used to execute a series of statements repeatedly until a specified condition is fulfilled. When utilizing the while loop, a condition must be supplied. The iterative procedure ends when the condition becomes false, and the next line of code is performed.
When the number of iterations is unknown, the while loop might be utilized.
How to Use while loop in Python
The while loop in Python is sometimes known as a pre-tested loop. Because there are no specified times provided, the loop will execute indefinitely if there is no condition.
A while loop’s syntax
while condition:
statements
Python while loop example
A basic while loop
Output:
Using the break statement: The break statement allows the loop to be halted even if the while condition is true.
Example:
Output:
Using the continue statement: The continue statement may be used to pause the iteration process and go to the next phase.
Example:
Output:
Extra Clauses
Else statement:
The “else” statement is an additional statement that may be added to the while loop’s syntax. This causes a certain command(s) to be executed once the provided condition in the while loop has turned false. Essentially, it is anything that is executed after the loop has been ended.
In Python, the while loop is used to execute statements while the provided condition is true. The else section of the statement is performed only when the while condition is false. Even if the user uses the break statement, the else block will not operate since it exits the loop, but the whole condition remains true. As a result, the else statement cannot be performed unless and until the condition of while becomes false.
Syntax of a python while loop
while condition:
# statements
else:
# statements
Example:
Multiple Conditions
The use of logical operators such as and & or allows you to expand the list of conditions in a while loop.
Making Use of Loop Control Statements
We’ll utilize and demonstrate the three loop control statements, break, continue, and pass.
Control Statement 1: Break
The break statement is used to break a loop before it reaches its conclusion.
This code will continually receive user input but will terminate if a negative integer is detected. An alternative method is provided below.
However, this is not always possible, which is why we have the break statement. The break statement is commonly used to handle unexpected inputs or when errors occur during execution.
Control Statement 2: Continue
The continue statement will terminate the current iteration of a loop and go to the next, skipping any statements in between.
Here’s a little example to explain the impact.
Output:
The number 2 is absent from the output because the continue command was performed, leading the loop to disregard everything and proceed to the next iteration.
Control Statement 3: Pass
Python’s structure requires that code blocks (if-else, def, for) not be empty. An error will occur if a code block is left unfilled.
The pass isn’t often used because it has few applications, but it’s nevertheless useful to know. If you want to create a code block but keep it empty for some time, simply include a pass statement in it.
As you can see in the example, the pass statement is included within the if statement. Perhaps the developer plans to add a block of code to the if statement, but he is leaving it empty for the time being. However, leaving it empty will result in an error, therefore use pass as a substitute.
Extra Examples:
Here are some examples to assist you to build your notions and comprehension.
Infinite loop problem
This will result in an endless loop owing to the absence of any increment. Because x will always be zero, the condition will always be true, giving in a continuous stream of 0s onscreen.
Calculating factorial
Try modifying this application to take the factorial number n! from the user. Remember to convert it to an integer before you use it.
Python do-while loop
The do-while loop is often called the post-tested loop in Python. In this case, the condition is tested only after the code has been executed. Although Python lacks the do-while loop, code may be developed to simulate the do-while condition.
The do-while loop differs from the while loop in that the statements in the while loop may not even be performed once if the needed condition is not satisfied. However, in the do-while loop, the loop will only execute once before the condition is verified.
The syntax of a do-while loop in Python is demonstrated below.
do {
#statement
} while (condition);
A do-while loop is terminated when the condition of the loop is found to be false or when a break statement is executed.
Example
How To End A While Loop Execution in Python
In python, we use the “break” statement whenever we want to end it’s execution.
Break is used to end the execution of a while loop. After the break statement, any other statement that falls within the same loop wouldn’t be executed. The only situation where the break leaves the loop is in the case of nested loops. This is where control is moved to the statement that comes immediately after the end of the loop.
Conclusion
The python while loop and the python do-while loop are fundamental looping techniques in python programming. Understanding the principles is critical since it will lead to the development of complicated programs to tackle real-world situations.
Python is an essential component of machine learning, artificial intelligence, and data analysis, thus anybody aspiring to be an expert in these subjects must embrace it as quickly as possible.