github.com/spotify/syslog-redirector-golang@v0.0.0-20140320174030-4859f03d829a/blog/content/slices/prog130.go (about)

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main
     6  
     7  import (
     8  	"fmt"
     9  )
    10  
    11  // Extend extends the slice by adding the element to the end.
    12  func Extend(slice []int, element int) []int {
    13  	n := len(slice)
    14  	if n == cap(slice) {
    15  		// Slice is full; must grow.
    16  		// We double its size and add 1, so if the size is zero we still grow.
    17  		newSlice := make([]int, len(slice), 2*len(slice)+1)
    18  		copy(newSlice, slice)
    19  		slice = newSlice
    20  	}
    21  	slice = slice[0 : n+1]
    22  	slice[n] = element
    23  	return slice
    24  }
    25  
    26  // Append appends the items to the slice.
    27  // First version: just loop calling Extend.
    28  func Append(slice []int, items ...int) []int {
    29  	for _, item := range items {
    30  		slice = Extend(slice, item)
    31  	}
    32  	return slice
    33  }
    34  
    35  func main() {
    36  	// START OMIT
    37  	slice1 := []int{0, 1, 2, 3, 4}
    38  	slice2 := []int{55, 66, 77}
    39  	fmt.Println(slice1)
    40  	slice1 = Append(slice1, slice2...) // The '...' is essential!
    41  	fmt.Println(slice1)
    42  	// END OMIT
    43  }