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

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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.

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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.

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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

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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.

Note: The else statement must start in the same line where the if statement ends.

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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

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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.

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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 } }

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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.