#4 – Learn Python With Practice – conditional structures

#4 – Learn Python With Practice – conditional structures

Following the previous lesson, we were asking how to check if the user has the same age as you for example :

def get_user_age():
	user_age = input("What is your age ? ")
    return user_age
    print("Maybe we have the same age !")
print(get_user_age())

If you didn’t understand well indentation in Python, you will understand them right now in this chapter …

We can excute some lines of our code with conditions, for example print « We have the same age » only if user’s age is the same us yours.

Start by running the following code in your computer :

a = 20
if a == 20:
	print("a is equal to 20")
print("End of program !")

You see ! It prints a is equal to 20 and End of program !

Change the value of a to 21 and run again your program.

a is equal to 20 is not printed, because the value of a is 21 and 21 is not equal to 20 !

We can compare variable to variable too :

a = 5
b = 5

if a == b:
	print("a is equal to b")

Please answer the following quiz then continue

DO NOT RUN THE CODE, TRY TO ANSWER BEFORE

a = 5
b = 5
c = 10
a = 10

if a == c:
	print("Nice to meet you!")
if a == b:
	print("Have a good day!")

Results

#1. What will the program above print ?

finish

Below a list of comporators is Python (and meany other languages)

  • a == b means a is equal to b
  • a != b means a is not equal to b
  • a > b means a is greater than b
  • a < b means a is less than b
  • a >= b means a is greater than or equal to b
  • a <= b means a is less than or equal to b

In the following example, we created three variables a, b, c and assigned them three values in order 20, 23, 17.

Then the c variable will take another value, please don’t run the code and guess what the program will print. (answer the quizz).

I want let you understand by yourself.

a = 20
b = 23
c = 17
c = a + 3

if b == c:
	print("b is equal to c")
if b != a:
	print("b is not equal to c")

Results

#1. What the program above will print ?

finish

The value of b is 23 and the value of c was 17 and has become 23 (20 + 3).

We compared the values b and c then we print b is equal to c if realy b is equal to c, otherwise we would print b is not equal to c.

a = 20
b = 23
c = 17
c = a + 3

if b == c:
	print("b is equal to c")
else:
	print("b is not equal to c")

The program above will do the same thing, try it!

if b is equal to c, print b is equal to c, otherwise (not equal means, greater than or less than).

Imagine if we want to check if b is equal to c and if b is not equal to c we want to check again if b is less than c.

a = 20
b = 22
c = 17
c = a + 3

if b == c:
	print("b is equal to c")
else:
	if b < c:
    	print("b is less than c")

That works, the program will show you b is less than c

note : I changed the value of b to 22.

We can write the same code in fewer lines in Python :

a = 20
b = 22
c = 17
c = a + 3

if b == c:
	print("b is equal to c")
elif b < c:
    	print("b is less than c")

elif in Python means else if.

a = 20
b = 22
c = 17
c = a + 3

if b == c:
	print("b is equal to c")
elif b < c:
    	print("b is less than c")
else:
	print("b is not equal to c and is not less than c, so it is greater than c")

Try the example above.

That’s all for conditional structures in Python for today, we will learn more and in deep by the next chapters.

Exercice

We take the example from the chapter #2 and let’s change it

print("This program will help you to create awesome resume and find \n new job")
user_name = input("What is your full name ?")
user_age = input("What is your age ?")
user_school = input("What is your school name ?")
user_looking_for_new_job = input("Are you looking for new job ?\n if yes tape 'YES'")

# let's print the user resume

print("Name : ", user_name)
print("age : ", user_age)
print("School : ", user_school)
print("Looking for new job : ", user_looking_for_new_job)

The program above will ask user for his information and show them as a resume.

In your resume, you wouldn’t print sentence like « Looking for new job: YES ».

We would like print I’m looking for new job as a software developer for example.

Your work now is to do some modifications in the previous example :

  • Check if the user_looking_for_new_job value is equal to « YES ».
  • If user_looking_for_new_job value is equal to « YES ». than print « Looking for a new job ».
print("This program will help you to create awesome resume and find \n new job")
user_name = input("What is your full name ?")
user_age = input("What is your age ?")
user_school = input("What is your school name ?")
user_looking_for_new_job = input("Are you looking for new job ?\n if yes tape 'YES'")

# let's print the user resume

print("Name : ", user_name)
print("age : ", user_age)
print("School : ", user_school)

if user_looking_for_new_job == "YES":
	print("Looking for new job : ", user_looking_for_new_job)

In the resume software we are developping, we ask user and print name, age, school and if he is looking for new job, how to list his experiences ?

That’s what we will see in next Chapter : #5 – Lists.

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