62 lines
1.6 KiB
Go
62 lines
1.6 KiB
Go
// For more tutorials: https://blog.learngoprogramming.com
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//
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// Copyright © 2018 Inanc Gumus
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// Learn Go Programming Course
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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//
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package main
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import (
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"fmt"
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"unsafe"
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s "github.com/inancgumus/prettyslice"
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)
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// type collection [4]string // #1
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type collection []string // #2
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// go is pass by copy
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// only the slice header is copied: 3 integer fields (24 bytes)
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// think of passing an array with millions of elements instead.
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func main() {
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// SliceHeader lives here:
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// https://golang.org/src/runtime/slice.go
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s.PrintElementAddr = true
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// #1
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data := collection{"slices", "are", "awesome", "period", "!!" /* #5 */}
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// data := collection{"slices", "are", "awesome", "period", "!!"}
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change(data) // #1
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s.Show("main's data", data) // #1
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fmt.Printf("main's data slice's header: %p\n", &data) // #3
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// ----------------------------------------------------------------------
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// #4
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array := [...]string{"slices", "are", "awesome", "period", "!!" /* #5 */}
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// array's size depends on its elements
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fmt.Printf("array's size: %d bytes.\n", unsafe.Sizeof(array))
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// slice's size is always fixed: 24 bytes (on a 64-bit system) — slice value = slice header
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fmt.Printf("slice's size: %d bytes.\n", unsafe.Sizeof(data))
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}
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// #1
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// passed value will be copied in the function
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func change(data collection) {
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// data is a new variable inside the function:
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// var data collection
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data[2] = "brilliant!"
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s.Show("change's data", data)
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fmt.Printf("change's data slice's header: %p\n", &data) // #3
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}
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