Go Operators
Operators are symbols that change or combine values. Assignment operators update a variable by using its current value.
Adding and taking one
The ++ statement raises the value by 1. The -- statement lowers it by 1.
package main
import "fmt"
func main() {
count := 5
count++
fmt.Println(count)
count--
fmt.Println(count)
}Updating in place
The += operator adds 6 to the total. The *= operator then multiplies the total by 3.
package main
import "fmt"
func main() {
total := 4
total += 6
fmt.Println(total)
total *= 3
fmt.Println(total)
}The remainder
The % operator gives what is left after division. Ten divided by three leaves one.
package main
import "fmt"
func main() {
fmt.Println(10 % 3)
}Parentheses change the order
Multiplication runs before addition in the first print. The parentheses make the addition run first in the second print.
package main
import "fmt"
func main() {
fmt.Println(2 + 3*4)
fmt.Println((2 + 3) * 4)
}Example
package main
import "fmt"
func main() {
items := 2
items += 3
fmt.Println("Items:", items)
items *= 2
fmt.Println("Doubled:", items)
fmt.Println("Left over:", items%3)
}Key points
- The ++ statement adds 1 to a variable.
- The -- statement takes 1 away from a variable.
- The += operator adds a value and stores the result.
- The *= operator multiplies a value and stores the result.
- The % operator gives the remainder after division.
- Parentheses change the order in which sums are worked out.
In this example, items starts at 2. The += operator adds 3, so items holds 5. The *= operator doubles that value to 10. The last print shows the remainder when 10 is split into groups of 3.
Note
++ and -- are statements in Go, so each one stands on its own line.
Try it Yourself
Edit the code, then press Run.
Running is simulated · Go Playground
Exercise
What is the value of x after x := 5 and then x++?