Step by Step solution about How to resolve the algorithm Substring/Top and tail step by step in the Go programming language

This Go program demonstrates string manipulation with both ASCII and UTF-8 encoded strings.

Here's a breakdown of the code:

1. ASCII Contents:

   • We define an ASCII string s with the value "ASCII".
   • Using string slicing, we remove the first byte (s[1:]) and the last byte (s[:len(s)-1]) to create new strings.
   • We also remove both the first and last bytes (s[1:len(s)-1]).

2. UTF-8 Contents:

   • We define a UTF-8 string u with the value "Δημοτική", which contains non-ASCII characters.
   • We use utf8.DecodeRuneInString to determine the size of the first rune in u. We then use this size to remove the first rune from u (u[sizeFirst:]).
   • Similarly, we use utf8.DecodeLastRuneInString to determine the size of the last rune in u and remove it (u[:len(u)-sizeLast]).
   • We also remove both the first and last runes (u[sizeFirst:len(u)-sizeLast]).

3. Output:

   • The program prints the original strings, the modified strings with the first byte/rune removed, the modified strings with the last byte/rune removed, and the modified strings with both the first and last byte/rune removed.

Key Concepts:

• ASCII vs. UTF-8: ASCII strings represent characters using 7-bit codes, while UTF-8 strings encode characters using a variable-length encoding that can represent characters from a wider range of languages.
• String Slicing: String slicing allows you to extract substrings from a given string using the [start:end] syntax.
• UTF-8 Rune Manipulation: The utf8 package provides functions for working with UTF-8 encoded strings. utf8.DecodeRuneInString and utf8.DecodeLastRuneInString are used to determine the size of runes in UTF-8 strings.

package main

import (
    "fmt"
    "unicode/utf8"
)

func main() {
    // ASCII contents:  Interpreting "characters" as bytes.
    s := "ASCII"
    fmt.Println("String:                ", s)
    fmt.Println("First byte removed:    ", s[1:])
    fmt.Println("Last byte removed:     ", s[:len(s)-1])
    fmt.Println("First and last removed:", s[1:len(s)-1])
    // UTF-8 contents:  "Characters" as runes (unicode code points)
    u := "Δημοτική"
    fmt.Println("String:                ", u)
    _, sizeFirst := utf8.DecodeRuneInString(u)
    fmt.Println("First rune removed:    ", u[sizeFirst:])
    _, sizeLast := utf8.DecodeLastRuneInString(u)
    fmt.Println("Last rune removed:     ", u[:len(u)-sizeLast])
    fmt.Println("First and last removed:", u[sizeFirst:len(u)-sizeLast])
}