Python while loop usage

The while loop is one of the loop structures in Python. The while loop continues until the expression becomes false. It expresses a logical expression and must return a true or false value. This article introduces the use of Python while loop to programmers. Friends who need it can read this article.

A loop is a structure that causes the first program to be repeated a certain number of times. The conditions continue to repeat themselves. When the condition becomes false, the loop ends and control of the program is passed to the statements following the loop.

while loop:

The while loop is one of the loop structures in Python. The while loop continues until the expression becomes false. It expresses a logical expression and must return a true or false value

The syntax of the while loop is:

while expression: 
  statement(s)

Here the expression statement is calculated first. If the expression is true, then the declaration block is executed repeatedly until the expression becomes false. Otherwise, the block of statements following the next statement is executed.

Note: In Python, all indented characters followed by spaces follow the same number of statements in a programming structure and are considered part of a single code block. Python uses indentation as its method of grouping statements.

For example:

#!/usr/bin/python 
 
count = 0
while (count < 9): 
  print &#39;The count is:&#39;, count 
  count = count + 1
 
print "Good bye!"

This will produce the following results:

The count is: 0
The count is: 1
The count is: 2
The count is: 3
The count is: 4
The count is: 5
The count is: 6
The count is: 7
The count is: 8
Good bye!

Until the count is no longer less than 9 blocks, it consists of print and increment statements and is executed repeatedly. Each iteration, the current value of the index count is displayed and then incremented by one.

Infinite Loop:

You must be cautious when using while loops because, this case never addresses the possibility of a false value use. This will cause a cycle that will never end. This loop is called an infinite loop.

An infinite loop may be useful in client/server programming where the server needs to run continuously so that client programs can communicate with it when necessary.

For example:

#!/usr/bin/python 
 
var = 1
while var == 1 : # This constructs an infinite loop 
  num = raw_input("Enter a number :") 
  print "You entered: ", num 
 
print "Good bye!"

This will produce the following results:

Enter a number :20
You entered: 20
Enter a number :29
You entered: 29
Enter a number :3
You entered: 3
Enter a number between :Traceback (most recent call last): 
 File "test.py", line 5, innum = raw_input("Enter a number :") 
KeyboardInterrupt

The above example will loop in infite, you will need to use Ctrl + C program to do that.

Single statement group: Similar to if statement syntax, if your simultaneous clause only contains a single statement, it can be placed on the same line,

Here is a The syntax of the row clause:

while expression : statement

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