Check Multiple Conditions in IF statement using Python

When writing programs, it is often necessary to check multiple conditions in order to determine the appropriate course of action. In Python, the "if" statement is used to execute a block of code if a specific condition is true. However, in many cases, we need to check more than one condition at a time, which can be accomplished using logical operators, parentheses, and other tools.

In this article, we will explore several techniques for checking multiple conditions within an "if" statement using Python. We will discuss the use of logical operators such as and, or, and not, as well as the use of parentheses to group conditions together. We will also cover the use of the "in" and "not" keywords to check if an item is in a list or string, as well as if-elif-else statements for checking multiple conditions in sequence.

By the end of this article, you should have a solid understanding of the various methods for checking multiple conditions within an if statement in Python. Whether you are a beginner programmer or an experienced developer, understanding these techniques will help you to write more effective and efficient code. So, let's dive in and explore the world of multiple condition checking in Python!

The Basic If Statement in Python

The basic syntax of the "if" statement in Python is −

if condition:
   # code to execute if condition is true

The condition in the "if" statement can be any expression that evaluates to a Boolean value (True or False). If the condition is True, the code block following the if statement will be executed. If the condition is False, the code block will be skipped.

Here is an example of a simple if statement in Python −

x = 5
if x > 0:
   print("x is positive")

In this example, we check if the value of x is greater than 0. If the condition is true, it will print the string "x is positive".

x is positive

Checking Multiple Conditions with Logical Operators

There are times when we need to check multiple conditions at the same time. In Python, we can use logical operators to combine multiple conditions in an if statement.

The three logical operators in Python are −

• and − returns True if both conditions are True

• or − returns True if at least one of the conditions is True

• not − returns the opposite of the condition

Let's look at some examples.

Example 1

In this example, we check if both x and y are greater than 0. If both conditions are true, we print the string "Both x and y are positive".

x = 5
y = 10
if x > 0 and y > 0:
   print("Both x and y are positive")

Output

It will produce the following output −

Both x and y are positive

Example 2

In this example, we check if at least one of x and y is greater than 0. If either condition is true, we print the string "At least one of x and y is positive".

x = 5
y = 10

if x > 0 or y > 0:
   print("At least one of x and y is positive")

Output

It will produce the following output −

At least one of the x and y is positive

Example 3

In this example, we check if x is not less than 0. If the condition is true, we print the string "x is not negative".

x = 5

if not x < 0:
   print("x is not negative")

Output

It will produce the following output −

x is not negative

Combining Multiple Conditions with Parentheses

We can also use parentheses to group conditions together in an "if" statement. This can be useful when we have complex conditions that need to be evaluated in a certain order. Let's take a look at an example.

Example

In this example, we check if both x and y are greater than 0 or if both x and y are less than 0. If either condition is true, we print the string "Both x and y are positive or both x and y are negative".

x = 5
y = 10

if (x > 0 and y > 0) or (x < 0 and y < 0):
   print("Both x and y are positive or both x and y are negative")

Output

It will produce the following output −

Both x and y are positive or both x and y are negative

Using the In Keyword to Check if an Item is in a List or String

Another way to check multiple conditions in an "if" statement is to use the in keyword. The "in" keyword is used to check if an item is in a list or a string.

Example 1

Here is an example of using the "in" keyword to check if an item is in a list. In this example, we check if "apple" is in the list of fruits. If the condition is true, we print the string "We have apples!".

fruits = ["apple", "banana", "orange"]
if "apple" in fruits:
   print("We have apples!")

Output

It will produce the following output −

We have apples!

Example 2

We can also use the "in" keyword to check if a substring is in a string. In this example, we check if the substring "fox" is in the string "The quick brown fox jumps over the lazy dog". If the condition is true, we print the string "We have a fox!".

sentence = "The quick brown fox jumps over the lazy dog"
if "fox" in sentence:
   print("We have a fox!")

Output

It will produce the following output −

We have a fox!

Using the Not Keyword to Check if an Item is Not in a List or String

We can also use the not keyword to check if an item is not in a list or string. Here is an example −

Example

In this example, we check if "mango" is not in the list of fruits. If the condition is true, we print the string "We don't have mangoes :(".

fruits = ["apple", "banana", "orange"]
if "mango" not in fruits:
   print("We don't have mangoes :(")

Output

It will produce the following output −

We don't have mangoes :(

Combining "in" and "not" Keywords

We can also combine the ‘in’ and ‘not’ keywords to check for more complex conditions. Here is an example −

Example

In this example, we check if "mango" is not in the list of fruits and if either "apple" or "orange" is in the list of fruits. If the condition is true, we print the string "We have apples or oranges, but no mangoes :(".

fruits = ["apple", "banana", "orange"]
if "mango" not in fruits and ("apple" in fruits or "orange" in fruits):
   print("We have apples or oranges, but no mangoes :(")

Output

It will produce the following output −

We have apples or oranges, but no mangoes :(

Using if-elif-else Statements to Check Multiple Conditions

When we need to check multiple conditions in sequence, we can use an if-elif-else statement. The syntax of an if-elif-else statement is −

if condition1:
   # code to execute if condition1 is true
elif condition2:
   # code to execute if condition1 is false and condition2 is true
else:
   # code to execute if both condition1 and condition2 are false

Now, let's take a look at some examples.

Example 1

In this example, we check if x is greater than 0. If the condition is true, we print the string "x is positive". If the condition is false and x is equal to 0, we print the string "x is zero". If both conditions are false, we print the string "x is negative".

x = 5
if x > 0:
   print("x is positive")
elif x == 0:
   print("x is zero")
else:
   print("x is negative")

Output

It will produce the following output −

"X is positive"

Example 2

In this example, we check if x is greater than 0. If the condition is true, we print the string "x is positive". If the condition is false and x is equal to 0, we print the string "x is zero". If both conditions are false, we print the string "x is negative".

x = -5
if x > 0:
   print("x is positive")
elif x == 0:
   print("x is zero")
else:
   print("x is negative")

Output

It will produce the following output −

"X is negative"

Example 3

In this example, we check if x is greater than 0. If the condition is true, we print the string "x is positive". If the condition is false and x is equal to 0, we print the string "x is zero". If both conditions are false, we print the string "x is negative".

x = 0
if x > 0:
   print("x is positive")
elif x == 0:
   print("x is zero")
else:
   print("x is negative")

Output

It will produce the following output −

"X is zero"

Conclusion

In conclusion, multiple condition checking is a crucial aspect of programming that allows us to create more complex and versatile programs. In Python, there are several ways to check multiple conditions within an if statement, including logical operators, parentheses, the in keyword, the not keyword, and if-elif-else statements.

By leveraging these techniques, we can create programs that are more flexible and able to handle a variety of situations. Additionally, understanding how to check multiple conditions effectively can make our code more efficient, reducing the likelihood of errors and bugs.

Overall, mastering the art of multiple condition checking in Python can greatly enhance our programming skills, allowing us to create more sophisticated programs that can handle diverse and complex scenarios.