If-Else

In Golang we have if-else statements to check a condition and execute the relevant code.

if statement

The if statement is used to check if a condition is met and execute the code inside the if block only if the condition is met.

The general syntax is

if <condition> {
    // Code to be executed if the condition is met.
}

Let us write a example code to test if we need to take an umbrella based on if it's raining or not outside.

isRaining := true

if isRaining {
    fmt.Println("It's raining, take an umbrella")
}

else statement

If the condition in a if statement is not met then we execute the else block if it is defined.

The syntax is

if <condition> {
    // code executes if condition is true
} else {
    // code executes if condition is false
}

One thing to remember here is the else statement should always be in the same line as the closing } of the if statement.

// below code doesn't work as else is not in the same line as if's closing }
if <condition> {
    // code executes if condition is true
} 
else {
    // code executes if condition is false
}

In the last module, we checked if it's raining and we gave a message if it is raining. But our code doesn't print anything if it is not raining. Let us fix it by adding an else statement and providing more information.

isRaining := true

if isRaining {
    fmt.Println("It's raining, take an umbrella")
} else {
    fmt.Println("It's not raining. Umbrella not needed")
}

Example

Let's write an example code to check if the user's name is John or not

userName := "John"

// prints You are John
if userName == "John" {
    fmt.Println("You are John")
} else {
    fmt.Println("You are not John")
}

// let's try again changing the username variable
userName := "Mathew"

// prints You are not John
if userName == "John" {
    fmt.Println("You are John")
} else {
    fmt.Println("You are not John")
}

You can cascade if statement in an else statement to check for more conditions and run the relevant code.

Now let's write some code to check if a user age is below 20 or between 20 and 60 or above 60.

userAge := 26

if userAge < 20 {
    fmt.Println("Below 20")
} else if userAge >= 20 && userAge <= 60 {
    fmt.Println("Between 20 and 60")
} else {
    fmt.Println("Above 60")
}

The if statement also provides an option to initialize a variable and test the condition within the if statement. The general syntax in this case is

if <init>;<condition> {
    // code to execute if condition is true
}

An example code is given below.

if userName := "Jeremy"; userName == "John" {
    fmt.Println("You are John")
} else {
    fmt.Println("You are not John")
}

Exercise

In a country, a person is allowed to vote if his/her age is above or equal to 18. Check the userAge variable and print "Eligible" if the person is eligible to vote or "Not Eligible" if the person is not eligible.