Lowercase English Letter Question

There are lots of questions which need to count occurence of English letters in a string. For the first thought, you may think of using map. However, we can take advantage of how language treat char, and we may be able to use array instead.

Here is ASCII table

We see 'a' has value of 97 and 'A' has value of 65

Count occurences of letters in a string which consists of lowercase English letters.

//for Java
var counts = new int[26];
for(char c: s.toCharArray()) counts[c-97]++;

//lower letter string to [26]int
func convertToLetterArr(s string) [26]int {
    
    var letters[26] int
    
    for _, c := range []rune(s) {
        
        letters[c-97]++
    }
    
    return letters
    
}