Python Loops

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Today we are going to look at another interesting program on python called the python loops. To begin with, a loop is a control structure that allows the compiler to repeat the execution of a statement or group of statements. They are two main types of loops which are the ‘for loop’ and the ‘while loop’.

1. The for loop

We can use the ‘for loop’ to execute programs which are in sequence data types such as lists, strings, or tuples.

Syntax

for val in sequence
statement(s)

The ‘for statement’ stores every value of each elements on the sequence until all the elements in the loop are exhausted. Let’s look at examples of for loop with data types

Loops with string

letter=('p','r','s','o','g','r')
for letter in 'programming':
  print('<', letter, '>')

OUTPUT

For loop with a tuple

color=('red','green','balck')

for x in color:
 print("I'm wearing a", x, "shirt")

print("multi-colored shirts are cool!")

OUTPUT

Using for loop with the range function

We can use the range function to know the exact numbers required by a loop.

x=15

total=0
for number in range(1, x+1):
  total+=number
print("sum of 1 and numbers from 1 to %d:%d"%(x, total))

OUTPUT

2. The while loop

The “while loop” is used when you need to repeatedly execute a statement or group of statements while the given condition is true.

Syntax

While conditions
     statements

Here is a program that adds number up to the desired number entered by the user. 

i = 2
while i < 8:
  print(i)
  i += 1

OUTPUT

Break statement

We used the break statement to end the present loop while instructing python to execute the first statement. It is commonly used to prevent the else statement.

Syntax 

break

Here is a loop that ends once it reaches the word ‘sloth’

animals=['lion', 'tiger','sloth','elephant']
for name in animals:
 if name=='sloth':
  break
 print('cool animal:', name)
print("Amazing animals!")

output

Continue statement

The compiler skips the specified iteration and takes all the other iterations.

Syntax

continue

Example

animals=['lion', 'tiger','elephant']
for name in animals:
 if name=='sloth':
  continue
 print('cool animal:', name)
print("Amazing animals!")

OUTPUT

Pass statement

It is an empty operation in python. The interpreter reads and executes the pass statements but returns nothing as the result. It is mostly used to mark codes that will eventually be written.

Syntax

Pass