Python for Loop Statements

Loop statement is used to repeat the statements N number of times.

  It has the ability to iterate over the items of any sequence, such as a list or a string.

  The for statement in Python differs a bit from what you may be used to in C or Java. Rather than giving the user the ability to define both the iteration step and halting condition (as C), Python?s for statement iterates over the items of any sequence (a list or a string), in the order that they appear in the sequence.


Syntax of Loop

for iterating_var in sequence:
             statements(s) 

The range() Function

If you do need to iterate over a sequence of numbers, the built-in function range() comes in handy. It generates arithmetic progressions


# Example of range() function 
seq=range(5) 
for n in seq:
	print(n)

# save file anyname.py
# open cmd and type : python anyname.py
0
1
2
3
4

The given end point in range function always excluded. range(5) : generates sequence of 1 to 4

Example: range(start, end)


# Example of range(start, end) function 
for i in range(1,6):
	print(i)

# save file anyname.py
# open cmd and type : python anyname.py
1
2
3
4
5

Example: printing the elements of list


# printing the elements of list
list=['java','python','php','dotnet']
for x in list:
	print(x)
java
python
php
dotnet

Example : print the numbers in reverse order

# printing the number in reverse order
print(list(range(10)))
for i in  range(10,0,-1):
	print(i)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
10
9
8
7
6
5
4
3
2
1

-1 in 3rd argument in range is used to change the direction of loop