从字符串字符和数字中提取字母

import re

string = "abc123def456"
letters = re.findall('[a-zA-Z]', string)
print(letters)

String string = "abc123def456";
String letters = "";

for (int i = 0; i < string.length(); i++) {
    char c = string.charAt(i);
    if (Character.isLetter(c)) {
        letters += c;
    }
}

System.out.println(letters);

var string = "abc123def456";
var letters = string.replace(/[^a-zA-Z]/g, "");

console.log(letters);