append_gotcha.go

package main

import "fmt"

func main() {
	fmt.Println("append gotcha\n")

	// not copying
	arr1 := []int{1, 2, 3}
	for i, _ := range arr1 {
		fmt.Println("prefix: ", arr1[:i])
		fmt.Println("suffix: ", arr1[i+1:])
		cp := append(arr1[:i], arr1[i+1:]...)
		fmt.Println("arr1: ", arr1)
		fmt.Println("cp: ", cp)
		fmt.Println("====")
	}

	fmt.Println("when copying\n")
	// copying
	arr1 = []int{1, 2, 3}
	for i, _ := range arr1 {
		fmt.Println("prefix: ", arr1[:i])
		fmt.Println("suffix: ", arr1[i+1:])
		cp := append([]int{}, arr1[:i]...)
		cp = append(cp, arr1[i+1:]...)
		fmt.Println("arr1: ", arr1)
		fmt.Println("cp: ", cp)
		fmt.Println("====")
	}
}

https://medium.com/@Jarema./golang-slice-append-gotcha-e9020ff37374

Make a new array by appending to a blank value.

use append only to append new value to given slice, not to create new one: