Loops and control statements (continue, break and walk) in Python

Loops | Python Methods and Functions | String Variables

While the loop


 while expression: statement (s) 

In Python, all statements indented by the same number of character spaces after the code construct are considered part of the same block of code. Python uses indentation as its method of grouping statements.

# prints Hello Geek 3 times

count = 0

while (count & lt; 3 ): 

count = count + 1

  print ( "Hello Geek" )


 Hello Geek Hello Geek Hello Geek 

See this is for an example where a while loop is used for iterators. As mentioned in the article, it is not recommended to use a while loop for iterators in python.

For in a loop

In Python there is no C style for loop, i.e. for (i = 0; i & lt; n; i ++). There is a for loop that looks like

# Loop through the list

print ( " List Iteration " )

l = [ " geeks " , "for" , "geeks" ]

for i in l:

  print (i)

# Iterate over a tuple (immutable)

print ( "Tuple Iteration" )

t = ( "geeks" , "for" , " geeks " )

for i in t:

print (i)

# Iterate over the line

print ( "String Iteration"

s = "Geeks"

for i in s:

print (i)

# Looping through the dictionary

print ( "Dictionary Iteration"

d = dict () 

d [ 'xyz' ] = 123

d [ 'abc' ] = 345

for i in d:

print ( "% s % d" % (i, d [i]))


 List Iteration geeks for geeks Tuple Iteration geeks for geeks String Iteration G eeks Dictionary Iteration xyz 123 abc 345 

We can use an in loop for custom iterators. See

from __ future__ import print_function

for i in range ( 1 , 5 ):

for j in range (i):

  print (i, end = '' )

  print ( )


 1 2 2 3 3 3 4 4 4 4 

Loop control statements

Loop control statements change execution from its normal sequence. When execution leaves a scope, all automatic objects created in that scope are destroyed. Python supports the following control statements.

Continue Statement
Returns the control to the beginning of the loop.


 Current Letter: g Current Letter: k Current Letter: f Current Letter: o Current Letter: r Current Letter: g Current Letter: k 

Break Statement
This brings control out of the loop

# Prints all letters except & # 39; e & # 39; and & # 39; s & # 39;

for letter in 'pythonengineering'

  if letter = = 'e' or letter = = 's' :


print ' Current Letter: ' , letter

var = 10


 Current Letter: e 

Pass Application
We use the pass statement to write empty loops. Pass is also used for empty control statement, function and classes.

for letter in 'pythonengineering'


# break the loop as soon as it sees" e "

  # or & # 39; s & # 39;

if letter = = 'e' or letter = = 's' :



print 'Current Letter:' , letter

# Empty loop

for letter in ' pythonengineering' :


print 'Last Letter:' , letter


 Last Letter: s 

How to print a list in reverse order (last to first element) using while and for loops.

This article contributed by Ashirvad Kumar. If you like Python.Engineering and would like to contribute, you can also write an article and mail it to [email protected] See my article appearing on the Python.Engineering homepage and help other geeks. 
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