For loop in python
problem
We wish to repeat actions/ commands. One way is by using the built-in loop mechanisms of Python. In this post we will use the well-known for loop.
SOLUTION
The for-loop is usually preferable when we know exactly how many times we wish to iterate. For example, we want to iterate 5 times and print a number each time. For example:
for num in range(5):
print(num)
running
In a terminal, issue the following command:
python3 for_loop.py
output
0
1
2
3
4
In the example above we used the range function in order to generate a range of numbers, hence the name. The range can be used in various ways.
iterating over a list
Let’s suppose we a list of numbers and we wish to print each item. We can easily plug the list in the for loop. For example:
numbers = [2, 11, -23, 89, 0, 466, 90]
for x in numbers:
print(x)
output
2
11
-23
89
0
466
90
print only even numbers by iterating over a list
Now, let’s extend the example above and print only the even numbers from the list. Remember an even number is a number that can be exactly divided by 2 (no remainder).
For example:
numbers = [2, 11, -23, 89, 0, 466, 90]
for x in numbers:
if x % 2 == 0: # check if even
print(x)
output
2
0
466
90
By simply adding an if statement in the loop’s body, we can now print only the even numbers from the list.
conclusion
In this post we saw how we can simply use the built-in for-loop mechanism of Python and how to iterate over a range of numbers or a given list of numbers. Pretty cool! 🧑🏻💻🇵🇾🐍
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Ellion
Professional IT consultant, writer, programmer enthusiast interested in all sorts of coding.
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