Python 101 Part 3

May 13, 2020   Python

We back again. we dive straight into loops.
In python we have 2 major loops: 

• While loop
• For loop (Mostly used)

WHILE LOOPS

With while loops, statements are executed while the conditions are True. 

e.g

i = 0

while i < 0:

    i+=1

    print(i)

let me breakdown down the code snippet:

• i = this is the variable. It is the indexing .
• while i < 0: = this is the statement which will be checked whether it checks out to True.
• i+=1 = this is to be executed when the condition doesn't check out to True.
• print(i) = displays output of the executed code.

Break

we use break to stop the loop amid the execution once a certain condition is met or check out to be True.

e.g 

i = 0

while i < 10:

  i+=1

  print(i)

  if i == 5:

      break

      print("You are halfway there")

 i +=1

Continue

continues with the execution even if the condition is True.

i = 0 

while i < 10:

i += 1

if (i == 5 ):

print(i,"You are halfway there")

continue

print(i)

Else

runs a the code when the condition is not True

i = 0 

while i < 10:

print(i)

i += 1

else:

print(i,"i is greater than 10")

FOR LOOP

A programmers' favorite loop because it loops everything :-), Anyway a for loop is a loop which iterates a sequence.

The difference between a for loop and a while loop is that a for loop doesn't require indexing unlike a while loop which you must provide a n indexing(Base of the loop).

Looping through a string.

e.g 

for x in "aimsec":

print(x)

let me break down this statement:

• for x in "aimsec": = this is the statement
• print(x) = this will print each and every character in the string "aimsec"

Break

With break, we can stop the looping before it has completed.

e.g

for x in "aimsec":

print(x)

if (x == "s"):

print("we stop here")

break

let me break it down:

• for x in "aimsec" = this statement iterates the string "aimsec" and assigning each character to x as a variable.
• print(x) = prints the variable
• if( x == "s") = this sets up a condition that if x == "s"
• print("We stop here") = this code is executed after which the condition is True
• break = this stops the iteration because the condition is True.

Continue

Were there is a break continue never misses.  :-), we use continue to continue the iteration after a condition is met in a loop.

e.g

for x in "aimsec":

if (x == "s"):

print(x, "is omitted")

continue

print(x)

Range( )

loops through a sequence from 0 to a specific number and increments by 1. 

for x in range(5):

print(x)

and in order to set a specific starting point in range you'll have to parse two arguments in the range function. e.g range(2, 5)

and for setting an incrementing value in the range, we parse 3 arguments e.g range(2, 5, 2)

Else

Executes a block of code when the loop is finished. e.g

for x in "aimsec":

print(x)

else:

print("Loop is complete")

Nested Loops

This is simply a loop inside a loop, whereby the inner loop is executed once at each iteration of the outer loop. e.g

for x in "aim":

for y in "sec":

print(x,y)

Pass

used instead of  empty space. and returns nothing :-)

e.g 

for x in "aimsec":

pass

Exercise: look into python conditional statements e.g IF, ELIF, ELSE
Stay tuned tomorrow we doing the IF statements.ADIOS!