Convert int to ASCII and back in Python

user_64911 0
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I'm working on making a URL shortener for my site, and my current plan (I'm open to suggestions) is to use a node ID to generate the shortened URL. So, in theory, node 26 might be short.com/z, node 1 might be short.com/a, node 52 might be short.com/Z, and node 104 might be short.com/ZZ. When a user goes to that URL, I need to reverse the process (obviously).

I can think of some kludgy ways to go about this, but I'm guessing there are better ones. Any suggestions?

encode ascii integer python
6 Answers

apparently I'm late to the party, jus like to share a snippet I use very often.

/**
 * 62 = 26 + 26 +10
 *
 * @param id
 * @return
 */
public String base62(long id) {
    StringBuilder sb = new StringBuilder();
    while (id >= 62) {
        int remainer = (int) (id % 62);
        id = id / 62;
        sb.append(index2char(remainer));
    }
    sb.append(index2char(id));

    return sb.reverse().toString();
}

public long reverseBase62(String s) {
    long r = 0;
    for (int i = 0; i < s.length(); i++) {
        r = r * 62;
        int index = char2index(s.charAt(i));
        if (index == -1) {
            throw new IllegalArgumentException(
                String.format("[%s] is in malformation, should only contain 0~9, a~z, A~Z", s));
        }
        r += index;
    }

    return r;
}
private char index2char(long index) {
    if (index < 10) {
        return (char) ('0' + index);
    }
    if (index < 36) {
        return (char) ('a' + index - 10);
    }
    return (char) ('A' + index - 36);
}



private int char2index(char c) {
    if ('0' <= c && c <= '9') {
        return c - '0';
    }
    if ('a' <= c && c <= 'z') {
        return c - 'a' + 10;
    }
    if ('A' <= c && c <= 'Z') {
        return c - 'A' + 36;
    }
    return -1;
}
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