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add: slice adv. ops. exercises

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Inanc Gumus
2019-03-05 23:32:32 +03:00
parent e379976af4
commit 9c96082326
19 changed files with 810 additions and 99 deletions
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119
16-slices/exercises/25-add-lines/main.go Normal file
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package main
import (
s "github.com/inancgumus/prettyslice"
)
// ---------------------------------------------------------
// EXERCISE: Add newlines to the lyric sentences
//
// You have a slice of lyrics data of Beatles' awesome
// song: Yesterday. Your goal is adding newlines after
// each sentence of the lyric.
//
// Your goal is creating a new slice, then copying
// each sentence of the lyric to the new buffer, then
// after each sentence adding a newline character.
//
// You cannot guess how many times you will get across
// something like this. Believe me, learning this will
// make you a better Gopher.
//
//
// RESTRICTIONS
//
// . For warming-up, in this exercise, never use the `append()` func.
//
// . Instead, only use the `copy()` func.
//
// . You cannot use slicing for printing the sentences.
//
// . Instead, use slicing to fill the new buffer, then print it.
//
//
// STEPS
//
// . Follow the instructions inside the code.
//
//
// EXPECTED OUTPUT
//
// yesterday all my troubles seemed so far away
// now it looks as though they are here to stay
// oh i believe in yesterday
//
// ---------------------------------------------------------
func main() {
//
// YOU DON'T NEED TO TOUCH THIS
//
// This inits some options for the prettyslice package.
// You can change the options if you want.
//
// s.Colors(false) // if your editor is light colored then enable this
s.PrintBacking = true // prints the backing arrays
s.MaxPerLine = 15 // prints max 15 elements per line
s.SpaceCharacter = "*" // print this instead of printing a newline (for debugging)
//
// UNCOMMENT THE VARIABLE BELOW THEN START!
//
// lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday`)
//
// RESTRICTION EXPLANATION:
//
// Don't do something like this:
// (Do not use slicing for printing the sentences)
//
// fmt.Println(lyric[:8])
// fmt.Println(lyric[8:18])
// fmt.Println(lyric[18:23])
// ========================================================================
//
// #1: CREATE A LARGE ENOUGH BUFFER (A NEW SLICE)
//
// You need to put each lyric sentence + a newline into this buffer
//
// I name the buffer: `fix`, you can name it however you want
// fix := make(...)
// ========================================================================
//
// #2: CALCULATE THE CUT POINTS
//
// You want to put newlines after each sentence. So you may want to put
// these index positions into a slice. Then you can use them to cut the
// lyric slice.
//
// cutpoints := []int{...}
// ========================================================================
//
// #3: CREATE A LOOP AND COPY THE SENTENCES INTO THE BUFFER
//
// for ... {
// Use the `copy` function to copy from the `lyric` slice to the buffer.
//
// Copy a newline character (in a string) to the buffer after each sentence.
//
// You can use slicing here for filling the new buffer.
//
// Uncomment this to aid debugging (to see how the fix slice changes)
// s.Show("fix slice", fix)
// }
// ========================================================================
//
// #4: PRINT THE BUFFER
//
// ...
}

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16-slices/exercises/25-add-lines/solution/main.go Normal file
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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"
"strings"
s "github.com/inancgumus/prettyslice"
)
func main() {
//
// YOU DON'T NEED TO TOUCH THIS
//
// This inits some options for the prettyslice package.
// You can change the options if you want.
//
// s.Colors(false) // if your editor is light colored then enable this
s.PrintBacking = true // prints the backing arrays
s.MaxPerLine = 15 // prints max 15 elements per line
s.SpaceCharacter = "*" // print this instead of printing a newline (for debugging)
lyric := strings.Fields(`yesterday all my troubles seemed so far away now it looks as though they are here to stay oh i believe in yesterday`)
// CREATE A LARGE ENOUGH BUFFER
// `+3` because we're going to add 3 newline characters
fix := make([]string, len(lyric)+3)
// CALCULATE THE CUT POINTS
//
// + The first sentence has 8 words so its cutpoint is 8.
//
// + The second one has 10 words so its cutpoint is 10.
//
// + The third one has 5 words so its cutpoint is 5.
//
//
// yesterday all my troubles seemed so far away now it looks as though they are here to stay
// |
// v
// cutpoint: 8
//
// ... now it looks as though they are here to stay oh i believe in yesterday
// |
// v
// 10
//
// ... now it looks as though they are here to stay oh i believe in yesterday
// |
// v
// 5
cutpoints := []int{8, 10, 5}
// `n` tracks how much we've moved inside the `lyric` slice
// `i` tracks the sentence that we're on
for i, n := 0, 0; n < len(lyric); i++ {
//
// copy to `fix` from the `lyric`
//
// destination:
// fix[n+i] because we don't want to delete the previous copy.
// it moves sentence by sentence, using the cutpoints.
//
// source:
// lyric[n:n+cutpoints[i]] because we want copy the next sentence
// beginning from the number of the last copied elements to the
// n+next cutpoint (the next sentence).
//
n += copy(fix[n+i:], lyric[n:n+cutpoints[i]])
// add a newline after the number of copied elements
// notice that the '\n' position slides as we move over
// that's why n+i
fix[n+i] = "\n"
// uncomment this to aid debugging (to see how the fix slice changes)
// s.Show("fix slice", fix)
}
// print the fix slice
for _, w := range fix {
fmt.Print(w)
if w != "\n" {
fmt.Print(" ")
}
}
}