Go if...else#

In computer programming, we use the if statement to run a block code only when a certain condition is met.

For example, assigning grades (A, B, C) based on marks obtained by a student.

• if the percentage is above 90, assign grade A
• if the percentage is above 75, assign grade B
• if the percentage is above 65, assign grade C

#Go if statement

The syntax of the if statement in Go programming is:

if test_condition {
   // code
}

If test_condition evaluates to

• true - statements inside the body of if are executed.
• false - statements inside the body of if are not executed.

#Example: Simple if statement in Golang

// Program to display a number if it is positive

package main
import "fmt"

func main() {
  number := 15

  // true if number is less than 0
  if number > 0 {
    fmt.Printf("%d is a positive number\n", number)
  }

  fmt.Println("Out of the loop")
}

Output

15 is a positive number
Out of the loop

In the above example, we have created a variable named number. Notice the condition,

number > 0

Here, since the variable number is greater than 0, the condition evaluates true.

If we change the variable to a negative integer. Let's say -5.

number := 5

Now, when we run the program, the output will be:

Out of the loop

This is because the value of number is less than 0. Hence, the condition evaluates to false. And, the body of the if block is skipped.

#Go if...else statement

The if statement may have an optional else block. The syntax of the if..else statement is:

if test_condition {
    // run code if test_condition is true
} else {
    // run code if test_condition is false
}

If test_condition evaluates to true,

• the code inside if is executed
• the code inside else is skipped

If test_condition evaluates to false,

• the code inside else is executed
• the code inside if is skipped

#Example: if...else statement in Golang

package main
import "fmt"

func main() {
  number := 10

  // checks if number is greater than 0
  if number > 0 {
    fmt.Printf("%d is a positive number\n", number)
  } else {
    fmt.Printf("%d is a negative number\n", number)
  }
}

Output

10 is a positive number

The number is 10, so the test condition number > 0 is evaluated to be true. Hence, the statement inside the body of if is executed.

If we change the variable to a negative integer. Let's say -5.

number := -5

Now if we run the program, the output will be:

-5 is a negative number

Here, the test condition evaluates to false. Hence code inside the body of else is executed.

#Go if...else if ladder

The if...else statement is used to execute a block of code among two alternatives.

However, if you need to make a choice between more than two alternatives, then we use the else if statement.

if test_condition1 {
   // code block 1
} else if test_condition2 {
   // code block 2
} else {
   // code block 3
}

Here,

if test_condition1 evaluates to true

• code block 1 is executed
• code block 2 and code block 3 are skipped

if test_condition2 evaluates to true

• code block 2 is executed
• code block 1 and code block 3 are skipped

if both test conditions evaluates to false

• code block 3 is executed
• code block 1 and code block 2 are skipped

#Example: if...if else ladder statement in Golang

// Program to relate two integers using =, > or < symbol

package main
import "fmt"

func main() {

  number1 := 12
  number2 := 20

  if number1 == number2 {
    fmt.Printf("Result: %d == %d", number1, number2)
  } else if number1 > number2 {
    fmt.Printf("Result: %d > %d", number1, number2)
  } else {
    fmt.Printf("Result: %d < %d", number1, number2)
  }
}

Output

Result: 12 < 20

Here, both the test conditions number1 == number2 and number1 > number2 are false. Hence the code inside the else block is executed.

#Go nested if statement

You can also use an if statement inside of an if statement. This is known as a nested if statement.

// outer if statement
if test_condition1 {
  // statements

  // inner if...else statement
  if test_condition2 {
    // statements
  }else {
    // statements
  }
}

#Example: Nested if statement in Golang

package main
import "fmt"

func main() {

  number1 := 12
  number2 := 20

  // outer if statement
  if number1 >= number2 {

  // inner if statement
  if number1 == number2 {
    fmt.Printf("Result: %d == %d", number1, number2)
    // inner else statement
  } else {
    fmt.Printf("Result: %d > %d", number1, number2)
  }

  // outer else statement
  } else {
    fmt.Printf("Result: %d < %d", number1, number2)
  }
}

Output

Result: 12 < 20

If the outer condition number1 >= number2 is true

• inner if condition number1 == number2 is checked
• if condition is true, code inside the inner if is executed
• if condition is false, code inside the inner else is executed

If the outer condition is false, the outer else statement is executed.