Fifth session of learning python

1. Loops in Python
Part ||
‫إعداد‬:
‫م‬.‫محمد‬ ‫علي‬

2. Objectives
 For loop statement with range
 While with is and is not
 If with for statements
 Break and continue

3. For loop with range
 As we saw at last video we can use range function with for loop and we
take an example for it
 Today we will take another examples:
 First example is the average of numbers from 1 to 10
 Second example is factor of number n!

4. Average for 1 to 10
 s=0
 for i in range(1,11):
 s=s+i
 su=s/10
 print(su)

5. Factor of number (n!)
 s=1
 for i in range(1,6):
 s=s*i
 print(s)

6. While with is and is not:
 As a Boolean operation we have the following operation in python
 is & not is
 We use is to make sure that two objects are same
 We use not is to make sure that two objects are not same
 We can use (int – string – float) as an objects
 Examples:

7.  >>> x=5
 >>> y=5
 >>> x is y
 True
 >>> x is not y
 False
 >>> a="ali"
 >>> b="Ali"
 >>> a is b
 False
 >>> a is not b
 True
 >>> c=3.5
 >>> d=3.4999999
 >>> c is d
 False
 >>> c is not d
 True

8. While with is and is not:
 To understood the usage of is and not is we will take the same example of
average of number and factor of number (n!) using while and (is) and (is
not)
 The program is written as following:

9. Average program
 s=1
 s1=11
 su=0
 while (s is not s1):
 su=s+su
 s+=1
 su=su/10
 print(su)

10. Factor of number (n!)
 s=1
 s1=6
 su=1
 while (s is not s1):
 su=su*s
 s+=1
 print(su)

11. If with for statements
 Also we can use if…else statement in for loop
 For example we can be sure that some number is in some range so we do
some thing for that
 Example:
s="t"
 s1="python"
 for i in s1:
 if s in s1:
 print("ok")
 else:
 print("some thing")

12. Break and continue
 The result for previous example is:
 ok
 ok
 ok
 ok
 ok
 ok
 That mean the (t) is in word (python) and repeat the result 6 times (length
of python world)

13. Break and continue
 What should we do to stop the loop when the program found (t)
 We must use break keyword
 break: stop the execution of loop for some reason
 The previous example will be like:
s="t"
 s1="python"
 for i in s1:
 if s in s1:
 print("ok")
 break
 else:
 print("some thing")
 And the result is:
 ok

14. Break and continue
 If we don’t want to print any thing if (t) in python what should we do
 We can use continue keyword
 Continue: to stop for a condition and continue after that
 Example: if we want to print 1 2 4 5 without 3
 We write:
for i in range(1,6):
 if i==3:
 continue
 print(i)

15. Break vs continue
 In the previous example if we use break instead of continue the result will
be like:
1
2
 Because break end all of loop but continue stop for condition and
continue over the loop