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add: slice internals last lectures

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Inanc Gumus
2019-02-15 16:30:11 +03:00
parent 288a41adf9
commit 17f6b93e46
6 changed files with 0 additions and 224 deletions
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31
x-tba/slices/11-slice-internals-3-len-cap/1-theory/main.go
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// For more tutorials: https://blog.learngoprogramming.com
//
// Copyright © 2018 Inanc Gumus
// Learn Go Programming Course
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
//
package main
import (
"fmt"
s "github.com/inancgumus/prettyslice"
)
func main() {
s.MaxPerLine = 6
s.PrintBacking = true
ages := []int{35, 15, 25}
s.Show("ages", ages)
s.Show("ages[0:0]", ages[0:0])
for i := 1; i < 4; i++ {
txt := fmt.Sprintf("ages[%d:%d]", 0, i)
s.Show(txt, ages[0:i])
}
s.Show("append", append(ages, 50))
}

56
x-tba/slices/11-slice-internals-3-len-cap/2-example/main.go
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// For more tutorials: https://blog.learngoprogramming.com
//
// Copyright © 2018 Inanc Gumus
// Learn Go Programming Course
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
//
package main
import (
s "github.com/inancgumus/prettyslice"
)
func main() {
s.PrintBacking = true
// ----------------------------------------------------
// #1 nil slice
var games []string // nil slice
s.Show("games", games)
// ----------------------------------------------------
// #2 empty slice
games = []string{} // empty slice
s.Show("games", games)
// s.Show("another empty", []int{})
// ----------------------------------------------------
// #3 non-empty slice
games = []string{"pacman", "mario", "tetris", "doom"}
s.Show("games", games)
// ----------------------------------------------------
// #4 reset the part using the games slice
// part is empty but its cap is still 4
part := games
s.Show("part", part)
part = games[:0]
s.Show("part[:0]", part)
s.Show("part[:cap]", part[:cap(part)])
for cap(part) != 0 {
part = part[1:cap(part)]
s.Show("part", part)
}
// #6 backing array's elements become inaccessible
// games = games[len(games):]
// ----------------------------------------------------
// #5 part doesn't have any more capacity
// games slice is still intact
s.Show("part", part)
s.Show("games", games)
}

22
x-tba/slices/12-slice-internals-4-append/1-theory/main.go
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// For more tutorials: https://blog.learngoprogramming.com
//
// Copyright © 2018 Inanc Gumus
// Learn Go Programming Course
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
//
package main
import (
s "github.com/inancgumus/prettyslice"
)
func main() {
s.PrintBacking = true
ages := []int{35, 15}
s.Show("ages", ages)
ages = append(ages, 5)
s.Show("append(ages, 5)", ages)
}

54
x-tba/slices/12-slice-internals-4-append/2-example/main.go
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@ -1,54 +0,0 @@
// For more tutorials: https://blog.learngoprogramming.com
//
// Copyright © 2018 Inanc Gumus
// Learn Go Programming Course
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
//
package main
import (
s "github.com/inancgumus/prettyslice"
)
func main() {
s.PrintBacking = true
// #1: a nil slice has no backing array
var nums []int
s.Show("no backing array", nums)
// #2: creates a new backing array
nums = append(nums, 1, 3)
s.Show("allocates", nums)
// #3: creates a new backing array
nums = append(nums, 2)
s.Show("free capacity", nums)
// #4: uses the same backing array
nums = append(nums, 4)
s.Show("no allocation", nums)
// GOAL: append new odd numbers in the middle
// [1 3 2 4] -> [1 3 7 9 2 4]
// #6: [1 3 2 4] -> [1 3 2 4 2 4]
nums = append(nums, nums[2:]...)
s.Show("nums <- nums[2:]", nums)
// #5: overwrites: [1 3 2 4 2 4] -> [1 3 7 9]
nums = append(nums[:2], 7, 9)
s.Show("nums[:2] <- 7, 9", nums)
// #7: [1 3 7 9] -> [1 3 7 9 2 4]
nums = nums[:6]
s.Show("nums: extend", nums)
}
// don't mind about these options
// they're just for printing the slices nicely
func init() {
s.MaxPerLine = 10
s.Width = 45
}

34
x-tba/slices/12-slice-internals-4-append/3-example-growth/main.go
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// For more tutorials: https://blog.learngoprogramming.com
//
// Copyright © 2018 Inanc Gumus
// Learn Go Programming Course
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
//
package main
import (
"math/rand"
"time"
s "github.com/inancgumus/prettyslice"
"github.com/inancgumus/screen"
)
func main() {
s.PrintBacking = true
s.MaxPerLine = 30
s.Width = 150
var nums []int
screen.Clear()
for cap(nums) <= 128 {
screen.MoveTopLeft()
s.Show("nums", nums)
nums = append(nums, rand.Intn(9)+1)
time.Sleep(time.Second / 4)
}
}

27
x-tba/slices/12-slice-internals-4-append/4-example-growth/main.go
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// For more tutorials: https://blog.learngoprogramming.com
//
// Copyright © 2018 Inanc Gumus
// Learn Go Programming Course
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
//
package main
import (
"fmt"
)
func main() {
ages, oldCap := []int{1}, 1.
for len(ages) < 5e5 {
ages = append(ages, 1)
c := float64(cap(ages))
if c != oldCap {
fmt.Printf("len:%-10d cap:%-10g growth:%.2f\n",
len(ages), c, c/oldCap)
}
oldCap = c
}
}