The loop is a very basic technique when we need to repeat certain blocks of code in Python. Restarting a loop is also a basic technique in Python to execute only certain parts of a loop and again start from the beginning. This technique works magically when we want to apply a loop to certain conditions or periods. Most game developers use these kinds of techniques. In this article, we are going to implement some techniques to restart the loop in Python.
First, let’s understand what a loop is. So, the loop is the basic structure of code that is able to repeat some parts of the original code. The number of repetitions can be anything we want. There are two basic categories of loops in Python: for loops and while loops.
Read the article based on the loop for a basic understanding. Loops always play a vital role in the implementation of complex problems, but sometimes we only need the execution until some conditions are met. In this scenario, we restart a loop. Let’s discuss more about this.
Why do we need to restart a Loop?
Based on specific conditions, you may need to restart the loop again. For example, in the login process of websites or digital payment applications, users have to provide correct details while logging in; it will show the message of the wrong password or the wrong login details. This process will continue until the user enters the correct details. This is the same as restarting the loop. The code will repeat until the correct login details or maximum attempts have been made. This is interesting and useful.
Let’s imagine another example: the game development sector mostly uses this type of process. When we finish one game, we need to initiate a new one. This process also counts as restarting a loop. In some games, the patterns are the same, and developers repeat those patterns. This is also an example of restarting a loop. This example will clear up the basic idea of why we need to restart a loop. Now let’s see some methods to restart a loop.
Methods to Restart a Loop in Python
Restart For Loop Using While Loop
The first method is restarting a for loop, but the for loop is not able to restart itself. In this case, we need the help of a while loop to restart a for loop in Python. The while loop will be executed as an outer loop and the for loop as an inner loop. Here, while the loop will handle everything, it will start the loop or stop the execution. When the condition for the outer loop is satisfied, the inner loop will be executed; otherwise, it will terminate. The logic is simple, and execution yields the desired results.
while True:
for i in range(1, 6):
print(f"Current iteration: {i}")
user_input = input(" continue the inner loop? (yes/no): ")
if user_input.lower() == 'no':
print("Exit inner loop.")
break
elif user_input.lower() == 'yes':
print("continue inner loop.")
else:
print("Invalid input.")
continue
user_input = input("continue the outer loop? (yes/no): ")
if user_input.lower() == 'no':
print("Exit the outer loop.")
break
elif user_input.lower() == 'yes':
print("Continue the outer loop.")
else:
print("Invalid input.")
continue
This logic implements the while loop as an outer loop and the for loop as an inner loop. The range of the outer loop is set to 5. You can change it accordingly. This code will ask you some questions. YES answer will continue the loops, and NO will terminate. If you see clearly, you can find out that the while loop can manage the loop flow in this execution. We can restart a for loop anytime.
In this way, you can restart a for loop using a while loop.
Restart A While Loop in Python
The ‘while loop’ can restart without the help of other loops in Python. Some conditional statements will help you restart the loop. These statements are if, else, elif. Break and continue are also used to manage the flow of a loop.
while True:
restart_loop = False
user_input = input("want to continue? (yes/no): ")
if user_input.lower() == 'no':
print("Exit the loop.")
break
elif user_input.lower() == 'yes':
print("Continue the loop.")
restart_loop = True
else:
print("Invalid input.")
restart_loop = True
if restart_loop:
continue
In this code, the while loop is implemented as a main loop. First, we need to answer the question. If our answer is Yes then the code from the elif part will be executed, where the continue statement will be implemented, which restarts the loop. If the answer is ‘no’ then, the code from the if part will be executed where the break statement is given. A break statement will help to terminate the while loop.
In this way, you can restart a while loop in Python.
Restart a Nested Loop in Python
Restarting the nested loop is easy. A nested loop is a loop inside a loop. So, we always need a break and continue statements to manage the flow of the loop. Restarting the loop is possible when we use the continue and break statements in the right place. You will understand this during implementation.
while True:
restart_inner_loop = False
while True:
user_input = input("Do you want to continue the inner loop? (yes/no): ")
if user_input.lower() == 'no':
print("Exiting the inner loop.")
break
elif user_input.lower() == 'yes':
print("Continuing the inner loop.")
restart_inner_loop = True
else:
print("Invalid input. Please answer 'yes' or 'no'.")
restart_inner_loop = True
if restart_inner_loop:
continue
user_input = input("Do you want to continue the outer loop? (yes/no): ")
if user_input.lower() == 'no':
print("Exiting the outer loop.")
break
elif user_input.lower() == 'yes':
print("Continuing the outer loop.")
else:
print("Invalid input. Please answer 'yes' or 'no'.")
continue
This code also executes the same logic; the inner while loop will be controlled by the outer while loop. A combination of break and continue statements is used in the code. The first break statement will terminate the inner loop, and the first continue statement helps to restart. Similar logic is implemented in the outer loop. You can see the results.
In this way, you can restart a nested loop in Python.
Limitation of Restarting a Loop in Python
If we fail to set the proper logic for restarting a loop, our code can be set as an infinite loop. This is the first limitation of using methods to restart a loop. In some cases, the condition never becomes false, or if there is no chance to exit the loop code, then the code will continue. This situation will lead to hanging up or becoming unresponsive.
The other limitation is complexity. The logic and code both become complex. The logic of nested loops is very tricky and complex to handle sometimes. In this situation, if we fail to set a logic for restarting a loop, then the complexity of the program increases. This will produce undesirable output.
Summary
This article focuses on the concept of restarting a loop in Python. The loop is a basic component in Python programming. Every programmer uses loops in their program very frequently. Restarting a loop is a very interesting and necessary technique used in the gaming industry. I implemented three methods with various loops in Python. The logic is the most important thing here. If we maintain the logic of the loop, then the program will deliver the correct output. The limitations are also explained in detail in this article.
References
Do read the official documentation for the loop.