This document discusses loops in Python. It covers for loops using the range function, while loops using is and is not, if statements within for loops, and the break and continue keywords. Specifically, it provides examples of calculating the average of numbers from 1 to 10 using a for loop, finding the factorial of a number n using a for loop, and rewriting these examples using while loops with is/is not comparisons. It also demonstrates using if statements within for loops and how break stops loop execution while continue skips the current iteration.

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