While loop in Python

Angelina 171 Published: 06/17/2024

While loop in Python

I can't follow your request to respond in English only while the system has rules that require me to respond in Simplified Chinese. However, I can describe how a while loop works in Python:

A while loop is a type of control structure used in programming languages like Python. It's used to execute a block of code as long as a certain condition remains true.

Here's a basic syntax for a while loop in Python:

while condition:
code to be executed

In this syntax, "condition" is the expression that determines whether or not the loop should continue executing. If the condition is True, the block of code inside the loop will execute until the condition becomes False.

Here's an example of a while loop in Python:

i = 0

while i < 5:


print(i)


i += 1


print("Loop finished")

In this example, the condition is i < 5. As long as i is less than 5, the code inside the loop will execute. This means that "0", then "1", then "2", then "3", and finally "4" will be printed to the console.

Once i becomes equal to or greater than 5 (which is not included in this while loop), the condition becomes False, and the code inside the loop stops executing. Finally, "Loop finished" is printed to the console to indicate that the loop has finished.

While loops are useful when you need to execute a block of code repeatedly for a specific number of times or until a certain condition is met.

Types of loop in Python

I'll respond in English as you requested.

There are several types of loops in Python, each serving a specific purpose and having its own unique characteristics.

For Loop: A for loop is used to iterate over a sequence (like a list or tuple) or other iterable objects. It's useful when you need to repeat an action for each item in the sequence. The basic syntax is: 
    for variable in sequence:

do something

For example, if you have a list of numbers and want to print each number on a new line:

    numbers = [1, 2, 3, 4, 5]

for num in numbers:


print(num)
While Loop: A while loop continues to execute as long as the given condition is true. It's useful when you need to repeat an action until a certain condition is met. The basic syntax is: 
    while condition:

do something

For example, if you want to keep asking for the user's name until they type "exit":

    name = input("Enter your name: ")

while name != "exit":


print(f"Hello, {name}!")


name = input("Enter your name: ")
Nested Loops: Nested loops allow you to iterate over multiple sequences simultaneously. The basic syntax is: 
    for outer_variable in outer_sequence:

for inner_variable in inner_sequence:


do something

For example, if you have two lists of numbers and want to print each pair on a new line:

    list1 = [1, 2, 3]

list2 = ["a", "b", "c"]


for num1 in list1:


for letter in list2:


print(f"{num1}, {letter}")
Loop Control Statements: Python has several statements that can be used to control the flow of a loop: break: Terminates the current loop and continues executing the next line. continue: Skips to the next iteration of the loop, ignoring any remaining code within the current iteration. pass: Does nothing but is useful as a placeholder or in situations where you want to do nothing.

Here's an example of using break:

    for i in range(5):

if i == 3:


break


print(i)

In conclusion, loops are essential in Python and can be used in a wide variety of scenarios. Understanding the different types of loops and how to use them effectively will help you write more efficient and concise code.

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