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 ofif
are executed.false
- statements inside the body ofif
are not executed.
![Working of if statement in Go Working of if statement in Go programming](/sites/tutorial2program/files/golang-if-statement.png)
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
The positive number is 15 Out of the loop
In the above example, we have created a variable named number. Notice the test_condition,
number > 0
Here, since the variable number is greater than 0, the test_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:
Keep Learning
This is because the value of number is less than 0. Hence, the test_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
![Working of if..else in Go Working of if...else in Go programming](/sites/tutorial2program/files/if-else-golang.png)
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.
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 executedcode block 2
andcode block 3
are skipped
if test_condition2 evaluates to true
code block 2
is executedcode block 1
andcode block 3
are skipped
if both test conditions evaluates to false
code block 3
is executedcode block 1
andcode block 2
are skipped
![Working of if..else if ladder in Go Working of if.. else if..else in Go programming.](/sites/tutorial2program/files/golang-if-else-ladder.png)
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
conditionnumber1 == number2
is checked - if condition is
true
, code inside the innerif
is executed - if condition is
false
, code inside the innerelse
is executed
If the outer condition is false
, the outer else
statement is executed.