In this lesson, we will learn about how to conditionally run code with if statements.

If Statements

If statements are used to perform an action when a condition is true. Imagine we are trying to decide if we need an umbrella.

```
Ask for the weather
if (It is raining) {
  Bring an umbrella
}
```

An if statement has the following format:

```
If (condition) {
  Action to perform if the condition is met
}
```

We define a condition, and code to run if that condition is met. When the condition is met, it is evaluated as `true`, when not, it is `false`. When the condition is `false`, the code in the brackets is not run. The previous example allows us to bring an umbrella when it is raining, and bring nothing when it is not.

Let's practice using an if statement to reach the flag.


So far we have seen if and else statements. But what if we want to check multiple conditions? We can use the else if statement which has the form:

```
If (condition) {
  Action to perform if some condition is met
} else if (second condition) {
  Action to perform if another condition is met
} …
```

The `…` at the next could be blank, an else statement, or another else if statement! Else if allows us to continue our checking of different conditions until one is met. An else statement provides actions to perform if no previous conditions are met.

For example, if we think about the weather:

```
If (It is sunny) {
  Bring sunglasses
} else if (It is raining) {
  Bring an umbrella
} else {
  Bring a sweater
}
```

We can use else if statements to help Codey make more advanced decisions!


Else If Statements

Conditions are not always met by the simple difference in values of numbers. Conditions are often far more complex than that! 

Let’s look at two common ways to create more powerful logical conditions, AND and OR operators.

Something like AND and OR operators allow us to combine conditions. The statements will look like:

* Condition1 AND Condition2
* Condtion1 OR Condtion2

**AND**

An AND condition only passes if *both* the left and right conditions are true. If either condition is false, the overall statement fails.

So for example :

```
If (it is cloudy AND the temperature is below 32) {
  snow
}
```

For this program, if either the sky is clear, or the temperature is too warm, it will not snow. The sky needs to be cloudy AND it needs to be very cold for snow to happen.

**OR**

The OR condition requires that at least one of two conditions is true for the whole statement to be true.

For example, if we think about our dentist appointments:

```
If (I am due for a cleaning OR I have a toothache) {
  go to the Dentist
}
```

We don't need multiple reasons to go to the dentist. We might go if it is time for our regular cleaning OR we might go because there is a problem. If both conditions were met, we'd have even more reason to go!

The logical operators allow us to combine conditions into more complex expressions. Let's practice getting Codey home.


Logical

An equality condition allows us to check whether two values are the same.

For example, imagine a store holding a sale every Wednesday. The cashier would need to compare whether the day "is equal to" Wednesday. In code, the phrase "is equal to" is often represented as "==". This code might look like.

```
Add up items
If Today == Wednesday {
  Apply Discount to purchase
}
Display total
```

Sometimes we want to define a condition in terms of check whether two values are *not* equal. For checking if values are different, we use != in code. Imagine we are trying to find an empty room for a meeting:

```
Go to conference room
If (room != empty) {
  Find a different room
}
Start meeting
```

Here, we would start a meeting if the room we found was empty, or we would have gone to a different room if someone was already there.

We use equality conditions when we need to see whether two values are the same. With Codey, we will check whether the block ahead is a hedge. Let's get started!


Equality

We often want to check if a value is above or below a certain amount. We check the relation of one value to another.

These kinds of conditions are known as *relational operators*. Languages typically use symbols from mathematics:

* For less than: `<`
* For less than or equal to: `<=`
* For greater than: `>`
* For greater than or equal to: `>=`

For example, if you go to the doctor and the nurse takes your temperature:

```
Take patient's temperature
If (body temperature is > 99) {
	Alert doctor to fever
}
Send in doctor
```

We can use relational operators to check whether values are higher or lower than each other. With Codey, we will compare their horizontal and vertical positions.


Relational

Congratulations! We are almost done with this lesson, but before we finish, let’s review if statements. We covered three types of if statements:

* **If**: provides actions to perform when a condition is met 
* **If/Else**: perform one action if the condition is met or another if the condition is not met
* **If/Else if**: allow us to check multiple conditions

We also covered three types of conditions for our if statements. The condition types are:

* **Equality**: check if two values are the same
* **Relational**: check if one value is less than or greater than another
* **Logical**: group conditions together with and/or statements
 
Let's use what we have learned to guide Codey to their final goal for this lesson!

Review

Sometimes our code needs to take different paths depending on the situation. Having our program respond to different conditions requires a new tool, if statements.

Throughout this lesson, we will discuss different types of conditions, as well as different types of if statements. There are three types of conditions used in if statements:

* Equality
* Relational
* Logical

These conditions are used to define different types of if statements. Types of if statements include:

* If
* Else
* Else if

In the next exercise, we will take a look at basic if and else statements. First, let's see the limitations of code without conditionals.


Introduction to If Statements

We've learned to use if statements to perform an action when a condition is met.

But what if we want something to happen when the condition is met, and something *else* to happen when the condition is not met? Else statements can be added to if statements.

```
If (condition) {
  Action to perform if the condition is met
} else {
  Action to perform if condition is not met
}
```

Imagine we are trying to go to the movies.

```
If (I have a car) {
  Drive to the theater
} else {
  Walk to the theater
}
Watch movie.
```

Here our code would have us drive if we have a car, or walk if we don't. We get there one way or another, then watch the movie.

Else statements help us define different paths for our code to follow. Let's practice getting Codey to their goal using if and else statements.
