Introduction To Python Part 4

Loops In Python

A loop allows us to execute a group of statements several times. Loops are often used on algorithms.

There are some types of loops in python:

1. for loop
2. while loop
3. nested loops

For Loop

A ‘for loop’ is used to execute statements once every iteration. We already know the number of iterations that are going to execute.

A for loop has two blocks, one is where we specify the conditions and then we have the body where the statements are specified which gets executed on each iteration.

for x in range(10):
print(x)

While Loop

The while loop executes the statements as long as the condition is true. We specify the condition at the beginning of the loop and as soon as the condition is false, the execution stops.

i = 1
while i < 6:
print(i)
i += 1
#the output will be numbers from 1-5.

Nested Loops

Nested loops are a combination of loops.

Following are a few examples of nested loops:

for i in range(1,6):
for j in range(i):
print(i , end = "")
print()
# the output will be
1
22
333
4444
55555

Conditional and Control Statements

Conditional statements in python support the usual logic in the logical statements that we have in python.

Following are the conditional statements that we have in python:

1. if
2. elif
3. else

if statement

x = 10
if x > 5:
print('greater')

The if statement tests the condition, when the condition is true, it executes the statements in the if block.

elif statement

x = 10
if x > 5:
print('greater')
elif x == 5:
print('equal')
#else statement
x =10
if x > 5:
print('greater')
elif x == 5:
print('equal')
else:
print('smaller')

When both if and elif statements are false, the execution will move to else statement.

Control statements

Control statements are used to control the flow of execution in the program.

Following are the control statements that we have in python:

1. break
2. continue
3. pass

break

name = 'edureka'
for val in name:
if val == 'r':
break
print(i)
#the output will be
e
d
u

The execution will stop as soon as the loop encounters break.

Continue

name = 'eduard'
for val in name:
if val == 'r':
continue
print(i)
#the output will be
e
d
u
a
r
d

When the loop encounters continue, the current iteration is skipped and the rest of the iterations get executed.

Pass

name = 'eduardo'
for val in name:
if val == 'r':
pass
print(i)
#the output will be
e
d
u
a
r
d
o

The pass statement is a null operation. It means that the command is needed syntactically but you do not wish to execute any command or code.

Now that we are done with the different types of loops that we have in python, let's understand the concept of functions in my next post.

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