# Conditionals in Python

Conditionals are control structures that allow a program to make decisions based on certain conditions.

These statements allow us to evaluate expressions and execute different blocks of code depending on whether these expressions are true or false.

In Python, conditionals are mainly implemented through the `if`, `elif` (short for “else if”), and `else` statements.

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## `if` Statement

The `if` statement is used to execute a block of code if a condition is true. The basic syntax is as follows:

``````if condition:
# block of code if the condition is true``````

For example, we can use an `if` to check if a number is greater than 10:

``````number = 15

if number > 10:
print("The number is greater than 10")``````

In this case, since the `number > 10` condition is true, the `print` will be executed and we will see “The number is greater than 10” in the output.

## `else` Statement

The `else` statement is used to execute a block of code when the condition in the `if` is false. The syntax is as follows:

``````if condition:
# block of code if the condition is true
else:
# block of code if the condition is false``````

Following the previous example, we could add an `else` to handle the case where the number is not greater than 10:

``````number = 5

if number > 10:
print("The number is greater than 10")
else:
print("The number is less than or equal to 10")``````

In this case, since `number` is 5 and the `number > 10` condition is false, the block of code inside the `else` will be executed and we will see “The number is less than or equal to 10” in the output.

## `elif` Statement

The `elif` statement is used to evaluate multiple conditions sequentially. It is a shortening of “else if”.

The syntax is as follows:

``````if condition_1:
# block of code if condition_1 is true
elif condition_2:
# block of code if condition_1 is false and condition_2 is true
else:
# block of code if all previous conditions are false``````

Let’s see an example where we use `elif` to classify a number in relation to 0:

``````number = 5

if number > 0:
print("The number is positive")
elif number < 0:
print("The number is negative")
else:
print("The number is zero")``````

In this case, since `number` is 5 and is greater than 0, the first block of code will be executed and we will see “The number is positive” in the output.

## Multiple Conditions

It is also possible to combine multiple conditions using the `and`, `or`, and `not` operators. These operators allow us to build more complex conditions:

• `and`: Returns `True` if both conditions are true.
• `or`: Returns `True` if at least one of the conditions is true.
• `not`: Returns `True` if the condition is false.

For example:

``````x = 10
y = 5
z = 0

if x > y and y > z:
print("All conditions are true")``````

In this case, all three conditions are true (`x > y`, `y > z`, and `x > z`), therefore, the `print` will be executed.