How to generate alphabet slice [closed] - go

Question

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 1 year ago.
Improve this question
I'm trying to generate an alphabet slice.
This is all I have so far
letters := []string{}
alphabet := []string{}
for i := 'A'; i <= 'Z'; i++ {
alphabet := append(letters, "a")
}
fmt.Println(alphabet)
This doesn't work. Can someone help me out?

Answer 1

Your program has some bugs because of which you're not getting the desired output. I've added comments to your code so that you can have a basic idea of where are you doing it incorrectly.
package main
import "fmt"
func main() {
// we don't really need the two slice
letters := []string{}
alphabet := []string{}
for i := 'A'; i <= 'Z'; i++ {
// alphabet declared but not used (compile error)
alphabet := append(letters, "a") // why hard-code "a"? wrong!
}
// print a slice of string? wrong!
// each character could be stored in byte or rune and then the slice could
// converted to string
fmt.Println(alphabet)
}
The following code might help:
package main
import "fmt"
func main() {
// Pre-allocate slice for storing 26 letters
// Note: Instead of []byte, we can use []rune as well
// But as our scope is limited to storing 'A' to 'Z' only
// byte is enought to hold each letter.
alphabet := make([]byte, 0, 26)
// Loop over 'A' to 'Z' and keep on appending
// to alphabet slice
var ch byte
for ch = 'A'; ch <= 'Z'; ch++ {
alphabet = append(alphabet, ch)
}
// Print alphabet
fmt.Println(string(alphabet))
}

Answer 2

With alphabet := append(letters, string(i)), you are creating a new object every time due to : and the outer one is not used.
alphabet := []string{}
for i := 'A'; i <= 'Z'; i++ {
alphabet = append(alphabet, string(i))
}
fmt.Println(alphabet)
Also, you don't need letters object as you can append on the alphabet as you go along and assign the returned object to itself.
Update: I agree with #shmsr that using string slice is an overkill if you just want to store a byte of data so you can use byte slice as:
alphabet := []byte{}
var i byte
for i = 'A'; i <= 'Z'; i++ {
alphabet = append(alphabet, i)
}
fmt.Println(string(alphabet)) // need explicit type conversion though else it prints ascii values by default
Note: You need an explicit type conversion though otherwise it prints ascii values by default.