The problem is simpler than it looks. You convert a rune value to an int value with int(r). But your code implies you want the integer value out of the ASCII (or UTF-8) representation of the digit, which you can trivially get with r – ‘0’ as a rune, or int(r – ‘0’) as an … Read more
That’s because you used Scanner.Scan() to read a rune but it does something else. Scanner.Scan() can be used to read tokens or runes of special tokens controlled by the Scanner.Mode bitmask, and it returns special constants form the text/scanner package, not the read rune itself. To read a single rune use Scanner.Next() instead: c := … Read more
See this example from Effective Go : for pos, char := range “日本語” { fmt.Printf(“character %c starts at byte position %d\n”, char, pos) } This prints : character 日 starts at byte position 0 character 本 starts at byte position 3 character 語 starts at byte position 6 For strings, the range does more work … Read more
Rune literals are just 32-bit integer values (however they’re untyped constants, so their type can change). They represent unicode codepoints. For example, the rune literal ‘a’ is actually the number 97. Therefore your program is pretty much equivalent to: package main import “fmt” func SwapRune(r rune) rune { switch { case 97 <= r && … Read more