Introduction
Variadic functions in Go are functions that can accept a variable number of arguments. They are useful when you don’t know beforehand how many arguments a function will receive. Variadic functions make it easier to handle functions that operate on an arbitrary number of elements, such as mathematical operations or string manipulations. In this chapter, you will learn the syntax and usage of variadic functions in Go, with examples to illustrate their application.
Syntax
A variadic function is defined by using ... before the type of the last parameter. This parameter is treated as a slice within the function.
Syntax:
func functionName(parameter1 type1, parameter2 type2, variadicParam ...type3) {
// function body
}
Examples
Basic Variadic Function
A simple example of a variadic function that sums an arbitrary number of integers.
Example:
package main
import "fmt"
func sum(nums ...int) int {
total := 0
for _, num := range nums {
total += num
}
return total
}
func main() {
fmt.Println(sum(1, 2, 3)) // Output: 6
fmt.Println(sum(1, 2, 3, 4, 5)) // Output: 15
}
Variadic Function with Regular Parameters
A variadic function can also have regular parameters along with the variadic parameter.
Example:
package main
import "fmt"
func greet(prefix string, names ...string) {
for _, name := range names {
fmt.Printf("%s %s\n", prefix, name)
}
}
func main() {
greet("Hello", "Alice", "Bob", "Charlie")
// Output:
// Hello Alice
// Hello Bob
// Hello Charlie
}
Passing a Slice to a Variadic Function
You can pass a slice to a variadic function by appending ... after the slice.
Example:
package main
import "fmt"
func sum(nums ...int) int {
total := 0
for _, num := range nums {
total += num
}
return total
}
func main() {
numbers := []int{1, 2, 3, 4, 5}
fmt.Println(sum(numbers...)) // Output: 15
}
Variadic Function with Mixed Types
While Go does not support variadic functions with mixed types directly, you can use an empty interface to achieve similar functionality.
Example:
package main
import "fmt"
func printAll(values ...interface{}) {
for _, value := range values {
fmt.Println(value)
}
}
func main() {
printAll(1, "hello", 3.14, true)
// Output:
// 1
// hello
// 3.14
// true
}
Conclusion
Variadic functions in Go provide a flexible way to handle functions that need to accept a variable number of arguments. They are useful for operations that need to process an arbitrary number of elements, such as summing numbers or printing values. By understanding how to define and use variadic functions, you can write more versatile and adaptable code. Whether dealing with simple or complex scenarios, variadic functions can help you manage variable argument lists effectively.