add: strings and projects
This commit is contained in:
Inanc Gumus
57
19-strings-runes-bytes/01-bytes-runes-strings-basics/main.go
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57
19-strings-runes-bytes/01-bytes-runes-strings-basics/main.go
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// 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 "fmt"
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func main() {
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str := "hey"
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bytes := []byte{104, 101, 121}
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// same as: []byte("hey")
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fmt.Printf(`"hey" as bytes : %d`+"\n", []byte(str))
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// same as: string([]byte{104, 101, 121})
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fmt.Printf("bytes as string : %q\n", string(bytes))
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// runes are unicode codepoints (numbers)
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fmt.Println()
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fmt.Printf("%c : %[1]d\n", 'h')
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fmt.Printf("%c : %[1]d\n", 'e')
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fmt.Printf("%c : %[1]d\n", 'y')
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// a rune literal is typeless
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// you can put it in any numeric type
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var (
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anInt int = 'h'
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anInt8 int8 = 'h'
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anInt16 int16 = 'h'
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anInt32 int32 = 'h'
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// rune literal's default type is: rune
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// so, you don't need to specify it.
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// aRune rune = 'h'
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aRune = 'h'
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// and so on...
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)
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fmt.Println()
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fmt.Printf("rune literals are typeless:\n\t%T %T %T %T %T\n",
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anInt, anInt8, anInt16, anInt32, aRune)
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fmt.Println()
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// all are the same rune
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// beginning with go 1.13 you can type: 0b0110_1000 instead
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// fmt.Printf("%q as binary: %08[1]b\n", 0b0110_1000)
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fmt.Printf("%q in decimal: %[1]d\n", 104)
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fmt.Printf("%q in binary : %08[1]b\n", 'h')
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fmt.Printf("%q in hex : 0x%[1]x\n", 0x68)
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}
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@ -0,0 +1,69 @@
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// 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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"os"
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"strconv"
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"strings"
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)
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func main() {
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var start, stop int
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if args := os.Args[1:]; len(args) == 2 {
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start, _ = strconv.Atoi(args[0])
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stop, _ = strconv.Atoi(args[1])
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}
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if start == 0 || stop == 0 {
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start, stop = 'A', 'Z'
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}
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fmt.Printf("%-10s %-10s %-10s %-12s\n%s\n",
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"literal", "dec", "hex", "encoded",
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strings.Repeat("-", 45))
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for n := start; n <= stop; n++ {
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fmt.Printf("%-10c %-10[1]d %-10[1]x % -12x\n", n, string(n))
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}
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}
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/*
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EXAMPLE UNICODE BLOCKS
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1 byte
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------------------------------------------------------------
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asciiStart = '\u0001' -> 32
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asciiStop = '\u007f' -> 127
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upperCaseStart = '\u0041' -> 65
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upperCaseStop = '\u005a' -> 90
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lowerCaseStart = '\u0061' -> 97
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lowerCaseStop = '\u007a' -> 122
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2 bytes
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------------------------------------------------------------
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latin1Start = '\u0080' -> 161
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latin1Stop = '\u00ff' -> 255
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3 bytes
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------------------------------------------------------------
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dingbatStart = '\u2700' -> 9984
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dingbatStop = '\u27bf' -> 10175
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4 bytes
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------------------------------------------------------------
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emojiStart = '\U0001f600' -> 128512
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emojiStop = '\U0001f64f' -> 128591
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*/
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@ -0,0 +1,72 @@
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// 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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"unicode/utf8"
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"unsafe"
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)
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func main() {
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str := "Yūgen ☯ 💀"
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// can't change a string
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// a string is a read-only byte-slice
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// str[0] = 'N'
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// str[1] = 'o'
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bytes := []byte(str)
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// can change a byte slice
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// bytes[0] = 'N'
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// bytes[1] = 'o'
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str = string(bytes)
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fmt.Printf("%s\n", str)
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fmt.Printf("\t%d bytes\n", len(str))
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fmt.Printf("\t%d runes\n", utf8.RuneCountInString(str))
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fmt.Printf("% x\n", bytes)
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fmt.Printf("\t%d bytes\n", len(bytes))
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fmt.Printf("\t%d runes\n", utf8.RuneCount(bytes))
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// fmt.Println()
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// for i, r := range str {
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// fmt.Printf("str[%2d] = % -12x = %q\n", i, string(r), r)
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// }
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fmt.Println()
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fmt.Printf("1st byte : %c\n", str[0]) // ok
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fmt.Printf("2nd byte : %c\n", str[1]) // not ok
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fmt.Printf("2nd rune : %s\n", str[1:3]) // ok
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fmt.Printf("last rune : %s\n", str[len(str)-4:]) // ok
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// disadvantage: each one is 4 bytes
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runes := []rune(str)
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fmt.Println()
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fmt.Printf("%s\n", str)
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fmt.Printf("\t%d bytes\n", int(unsafe.Sizeof(runes[0]))*len(runes))
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fmt.Printf("\t%d runes\n", len(runes))
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fmt.Printf("1st rune : %c\n", runes[0])
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fmt.Printf("2nd rune : %c\n", runes[1])
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fmt.Printf("first five : %c\n", runes[:5])
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fmt.Println()
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word := "öykü"
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fmt.Printf("%q in runes: %c\n", word, []rune(word))
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fmt.Printf("%q in bytes: % [1]x\n", word)
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fmt.Printf("%s %s\n", word[:2], []byte{word[0], word[1]}) // ö
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fmt.Printf("%c\n", word[2]) // y
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fmt.Printf("%c\n", word[3]) // k
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fmt.Printf("%s %s\n", word[4:], []byte{word[4], word[5]}) // ü
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}
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46
19-strings-runes-bytes/04-rune-decoding/01/main.go
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46
19-strings-runes-bytes/04-rune-decoding/01/main.go
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@ -0,0 +1,46 @@
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// 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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"unicode/utf8"
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)
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func main() {
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const text = `Galaksinin Batı Sarmal Kolu'nun bir ucunda, haritası bile çıkarılmamış ücra bir köşede, gözlerden uzak, küçük ve sarı bir güneş vardır.
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Bu güneşin yörüngesinde, kabaca yüz kırksekiz milyon kilometre uzağında, tamamıyla önemsiz ve mavi-yeşil renkli, küçük bir gezegen döner.
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Gezegenin maymun soyundan gelen canlıları öyle ilkeldir ki dijital kol saatinin hâlâ çok etkileyici bir buluş olduğunu düşünürler.`
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r, size := utf8.DecodeRuneInString("öykü")
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fmt.Printf("rune: %c size: %d bytes.\n", r, size)
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r, size = utf8.DecodeRuneInString("ykü")
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fmt.Printf("rune: %c size: %d bytes.\n", r, size)
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r, size = utf8.DecodeRuneInString("kü")
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fmt.Printf("rune: %c size: %d bytes.\n", r, size)
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r, size = utf8.DecodeRuneInString("ü")
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fmt.Printf("rune: %c size: %d bytes.\n", r, size)
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// for range loop automatically decodes the runes
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// but it gives you the position of the current rune
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// instead of its size.
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// for _, r := range text {}
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for i := 0; i < len(text); {
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r, size := utf8.DecodeRuneInString(text[i:])
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fmt.Printf("%c", r)
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i += size
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}
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fmt.Println()
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}
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@ -0,0 +1,57 @@
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package main
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import (
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"bytes"
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"fmt"
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"testing"
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"unicode"
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"unicode/utf8"
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)
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/*
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Let's run this program to see the speed differences.
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benchDecoder 30000000 46.2 ns/op --> BEST
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benchForRange 30000000 53.0 ns/op --> MEDIOCRE
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benchConcater 20000000 93.7 ns/op --> WORST
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*/
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var word = []byte("öykü")
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func decoder(w []byte) {
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_, size := utf8.DecodeRune(word)
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copy(w[:size], bytes.ToUpper(w[:size]))
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}
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func forRange(w []byte) {
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var size int
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for i := range string(w) {
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if i > 0 {
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size = i
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break
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}
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}
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copy(w[:size], bytes.ToUpper(w[:size]))
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}
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var globalString string
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func concater(w []byte) {
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runes := []rune(string(w))
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runes[0] = unicode.ToUpper(runes[0])
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globalString = string(runes)
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}
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func bench(technique func([]byte)) testing.BenchmarkResult {
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return testing.Benchmark(func(b *testing.B) {
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for i := 0; i < b.N; i++ {
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technique(word)
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}
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})
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}
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func main() {
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fmt.Println("benchDecoder", bench(decoder))
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fmt.Println("benchForRange", bench(forRange))
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fmt.Println("benchConcater", bench(concater))
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}
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43
19-strings-runes-bytes/04-rune-decoding/02/main.go
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43
19-strings-runes-bytes/04-rune-decoding/02/main.go
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@ -0,0 +1,43 @@
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// 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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"bytes"
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"fmt"
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"unicode/utf8"
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)
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func main() {
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word := []byte("öykü")
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fmt.Printf("%s = % [1]x\n", word)
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// how to make the first rune uppercase?
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// you need to find the starting and ending position of the first rune
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// 1st way: `for range`
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// you can't get the runes by range overing a byte slice
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// first, you need to convert it to a string
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var size int
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for i := range string(word) {
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if i > 0 {
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size = i
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break
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}
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}
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// 2nd way: let's do it using the utf8 package's DecodeRune function
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_, size = utf8.DecodeRune(word)
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// overwrite the current bytes with the new uppercased bytes
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copy(word[:size], bytes.ToUpper(word[:size]))
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// to get printed bytes/runes need to be encoded in a string
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fmt.Printf("%s = % [1]x\n", word)
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}
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45
19-strings-runes-bytes/05-internals/main.go
Normal file
45
19-strings-runes-bytes/05-internals/main.go
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@ -0,0 +1,45 @@
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// 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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)
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func main() {
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// empty := ""
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// dump(empty)
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hello := "hello"
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dump(hello)
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dump("hello")
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dump("hello!")
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for i := range hello {
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dump(hello[i : i+1])
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}
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dump(string([]byte(hello)))
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dump(string([]byte(hello)))
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dump(string([]rune(hello)))
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}
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// StringHeader is used by a string value
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// In practice, you should use: reflect.Header
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type StringHeader struct {
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// points to a backing array's item
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pointer uintptr // where it starts
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length int // where it ends
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}
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// dump prints the string header of a string value
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func dump(s string) {
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ptr := *(*StringHeader)(unsafe.Pointer(&s))
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fmt.Printf("%q: %+v\n", s, ptr)
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}
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Reference in New Issue
Block a user