muathkhatib/CF-01-Python-Looping-Statements

Python Looping Statements

In Python, the iterative statements are also known as looping statements or repetitive statements. The iterative statements are used to execute a part of the program repeatedly as long as a given condition is True.

Python provides the following iterative statements.

1. While loops
2. For loops

While Loops

In Python, the while statement is used to execute a set of statements repeatedly. the while statement is also known as entry control loop statement because in the case of the while statement,

first, the given condition is verified then the execution of statements is determined based on the condition result.

The general syntax of while statement in Python is as follows.

Syntax

while condition:
        Statement_1
        Statement_2
        Statement_3
        ...

Flow chart Example

Code example

i = 1
while i < 10:
    print(i)
    i = i + 1
print('Value less than 10')

What is the statements in While Loop

1. break statement

With the break statement we can stop the loop even if the while condition is true:

i = 1
while i < 6:
  print(i)
  if i == 3:
    break
  i += 1

2. else statement

With the else statement we can run a block of code once when the condition no longer is true:

i = 1
while i < 6:
  print(i)
  i += 1
else:
  print("i is no longer less than 6")

3. continue statement

With the continue statement we can stop the current iteration, and continue with the next:

i = 0
while i < 6:
    i = i + 1
    if i == 3:
        continue
print(i)

For Loops

In Python, the for statement is used to iterate through a sequence like a list, a tuple, a set, a dictionary, or a string. The for statement is used to repeat the execution of a set of statements for every element of a sequence.

The general syntax of for statement in Python is as follows.

Syntax

for <variable> in <sequence>:
        Statement_1
        Statement_2
        Statement_3
        ...

Flow chart Example

Example

#Print each fruit in a fruit list:

fruits = ["apple", "banana", "cherry"]
for x in fruits:
  print(x)

What statments and functions we are using with for !

1. break Statement

With the break statement we can stop the loop before it has looped through all the items:

fruits = ["apple", "banana", "cherry"]
for x in fruits:
  print(x)
  if x == "banana":
    break

fruits = ["apple", "banana", "cherry"]
for x in fruits:
  if x == "banana":
    break
  print(x)

2. continue Statement

With the continue statement we can stop the current iteration of the loop, and continue with the next:

fruits = ["apple", "banana", "cherry"]
for x in fruits:
  if x == "banana":
    continue
  print(x)

3. range Function

To loop through a set of code a specified number of times, we can use the range() function, The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number.

for x in range(6):
  print(x)

for x in range(2, 6):
  print(x)

for x in range(2, 30, 3):
  print(x)

4. Else in For Loop

The else keyword in a for loop specifies a block of code to be executed when the loop is finished:

for x in range(6):
  print(x)
else:
  print("Finally finished!")

for x in range(6):
  if x == 3: break
  print(x)
else:
  print("Finally finished!")