TL;DR – The Python if else statement executes a function based on a certain true-false condition.
Contents
What is the Python if else statement?
The Python if else
statement is an extended version of the if
statement. While the Python if
statement adds the decision-making logic to the programming language, the if else
statement adds one more layer on top of it.
Both of them are conditional statements that check whether a certain case is true or false. If the result is true, they will run the specified command. However, they perform different actions when the set condition is false.
When an if
statement inspects a case that meets the criteria, the statement will execute the set command. Otherwise, it will do nothing. Look at this basic example of Python if statement:
Meanwhile, the if else
statement will execute another specified action if it fails to meet the first condition.
Simply put, the if else
statement decides this: if something is true, do something; if something is not true, then do something else.
Note: the
else
will only run when the case does not meet the condition of theif
statement.
If else in Python: learn the syntax
Single condition example
For a single condition case, specify the case condition after the if
statement followed by a colon (:). Then, fill another specified action under the else
statement. Here's how the code structure should look like:
if <a specific case>:
<execute this command>
else:
<perform a different command>
Replace <a specific case>
with the conditions you want to examine, and <execute this command>
with the action that should be done if the case is TRUE. Then, replace <perform a different command>
with the actions that should be done if the case is FALSE.
Here is an example of applying Python if else
statements. In this case, the if
statement is printed because it fits the primary condition:
c = 5
if(c > 4):
print("Value of c is greater than 4")
else :
print("Value of c is 4 or less")
In the following example, we make the code execute the else
command by making the primary condition false:
c = 3
if(c > 4):
print("Value of c is greater than 4")
else :
print("Value of c is 4 or less than 4")
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Checking multiple conditions with if else and elif
To check multiple if
conditions, you can use the Python elif
in the middle of the if else
function instead of creating a lot of if
statements as a big loop. The code will look like this:
Note:
elif
is short forelse if
.
if <a specific case>:
<do this statement>
elif <a different case>:
<execute another statement>
else:
<do something else>
Replace <a different case>
with the second condition you want to use, and <execute another statement>
with the action that should be carried out if the second case is TRUE. Then, the rest goes the same as with the single if else
condition example we mentioned first.
The following example shows the use of Python if else
and also elif
:
x = int(input("Please input the weight of your package."))
if x >= 120:
print('This size exceeds our limitations.')
elif x >= 50:
print('You need to pay a fee of $20 for this package.')
else:
print("There is no extra charge for the delivery.")
The program above will run once. If you need to run it multiple times, you would need to use for
or while statements.
Note: Python does not use curly brackets ({}) to mark code initiation. Instead, it uses indentation.
A common if else use in Python
Python if else
statement is widely used for sorting comparisons of operators: greater than, less than, equal to, greater than or equal to, less than or equal to, etc.
Let's say you want to evaluate some examination results. You want to automatically convert the score numbers into letters. The code would look like this:
x = int(input("What is your exam score?"))
if x >= 85:
print('You got an A! Congrats!')
elif x >= 75:
print('You got a B! Well done!')
elif x > 50:
print('You got a C. Not great, not terrible.')
elif x == 50:
print('You got a D. But you can do better!')
else:
print("You did not pass the exam. See the teacher for more information.")
- The function will output A if the score is greater than or equal to 85.
- If the score is greater than or equal to 75, it will output B.
- It will display C if the score is greater than 50.
- D will be shown if the score is equal to 50.
- If the score is less than 50, the function will print that the student did not pass his/her exam.
Python if else: useful tips
- Always use a colon (:) at the end of every
if
line. - You can add as many Python
elif
conditions as you want to check more options.