Python Assignment Operators
An assignment operator is a sign that stores a new value in a variable. Short signs like += do the maths and store the answer back.
Updating the long way
Each update repeats the name on both sides of =.
score = 10
score = score + 5
score = score + 5
print(score)Give a value
One equals sign stores a value in a variable.
score = 10
print(score)Add to a variable
Read score += 5 as score = score + 5.
score = 10
score += 5
print(score)Take away, then multiply
Each line updates the value that is already stored.
price = 20
price -= 5
print(price)
price *= 2
print(price)Divide shortcuts
The sign /= gives a float. The sign //= gives a whole number.
total = 20
total /= 4
print(total)
count = 17
count //= 5
print(count)A remainder shortcut
This keeps only the minutes left after whole hours.
minutes = 75
minutes %= 60
print(minutes)Example
balance = 200
print("Start:", balance)
balance += 80
print("Month 1:", balance)
balance += 80
print("Month 2:", balance)
balance += 120
print("Month 3:", balance)Key points
- Assignment operator: a sign that stores a new value in a variable.
- Use = to store a value in a variable.
- The signs +=, -=, *=, /=, //= and %= each update the variable on the left.
- Read x += 1 as x = x + 1.
- Both lines do the same job.
- Use these shortcuts when a value needs to grow or shrink by one step.
In this example, the balance starts at 200. Python adds 80 for month 1 and the balance is 280. It adds 80 again for month 2 and the balance is 360. It adds 120 for month 3 and the balance is 480.
Note
/= always gives a float, just like /.
A whole number can become a float after /=
Try it Yourself
Edit the code, then press Run.
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Exercise
A variable x holds 8. After x *= 3, what does x hold?