In this tutorial we look at how to use the
elif statements in Python.
When coding in any language, there are times when we need to make a decision and execute some code based on the outcome of the decision.
In Python, we use the
if statement to evaluate a condition.
Python If Statement
The syntax of the
if statement in Python is:
if condition: statement
Pay particular attention to the semi-colon
: and the indentation.
We use the logical operators to evaluate a condition. The logical operators are:
a == b
- Not Equals:
a != b
- Less than:
a < b
- Less than or equal to:
a <= b
- Greater than:
a > b
- Greater than or equal to:
a >= b
The code following the
if statement is executed only if the condition evaluates to
if statement in Python:
password = 'Hello' if len(password) < 6: print('password too weak - should be at least 6 characters')
password too weak - should be at least 6 characters
In the above code, we are evaluating the length of a password. The condition is that, the length should not be less than 6 characters long.
This is denoted by the less than operator
Since the string “Hello” is less than 6 characters, then the condition evaluates to true and hence we see the print statement.
Python If…Else Statement
If the result of an evaluation is false and we want to action on the result, then we include an
The syntax of the
if...else statement looks like:
if condition: statement_1 else: statement_2
So, continuing with the same example above, if we wanted to let the user know that their password has met the required length, we put that in the
password = 'Mission' if len(password) < 6: print('password too weak - should be at least 6 characters') else: print('your password was accepted')
your password was accepted
In this case, the word “Mission” has 7 characters so our
if condition evaluates to false. Because we have an
else block, then the second
print() statement is executed.
Multiple If…Else With Elif
When a program needs to handle more than two cases, we need to use multiple
else blocks. The keyword
elif means else if.
For example, we have a program that needs to determine the type of a triangle based on 3 integer inputs.
- Scaling triangle is one where all three sides have different lengths
- Isosceles triangle has two sides of the same length
- Equilateral triangle is one where all the sides are equal
a = 5 b = 5 c = 5 if a != b and b != c and a != c: print('This is a scalene triangle') elif a == b and b == c: print('This is an equilateral triangle') else: print('This is an isosceles triangle')
This is an equilateral triangle
This example illustrates how to handle more than two cases. Like before, remember the
: and the indentations.
There is no limit on the number of
elifs that we can use. There must only be one
else statement which serves as a catch-all. If all the
if statements fail, then the
else statement is executed.
Python Ternary Operator (Shorthand If…Else)
If we have an
if...else block, we can use the ternary operator and write the
if...else block in one line.
The syntax is:
condition_if_true if condition else condition_if_false
a = 100 b = 200 print('A') if a > b else print('B')
elifstatements control the program flow.
- The if statement in programming is used for decision making.
- The if statement is evaluated on the basis of the specified condition(s).
- The else block can be attached with the if statement and it is executed if the condition is false.
- The else block cannot exist with the if statement.
- The elif statement(s) can be attached with the if statement if there are multiple conditions.