Recursion

Functions that call themselves - Go supports recursion with automatic goroutine stack growth, though deep trees are better handled with an explicit stack.

A recursive function calls itself to solve a smaller version of a problem. A base case stops the calls. This factorial function expects a nonnegative input.

Each recursive call reduces n by one until it reaches the base case, zero.

package main
 
import "fmt"
 
func factorial(n int) int {
    if n == 0 {
        return 1
    }
    return n * factorial(n-1)
}
 
func main() {
    fmt.Println(factorial(5))
}

In production

Go grows call stacks as needed, but deep recursion can still exhaust available memory or reach runtime limits. Use a loop or explicit stack when input depth is unbounded. This example can also overflow int for large values, so validate its input range.

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