Why use integers for tokens?

Question

Is there a good reason to use numbers to identify tokens now? I follow Crafting a Compiler.

The code submitted by the author is here:

public class Token {
    public final static int ID = 0, FLTDCL = 1, INTDCL = 2, PRINT = 3,
            ASSIGN = 4, PLUS = 5, MINUS = 6, EOF = 7, INUM = 8, FNUM = 9;

    public final static String[] token2str = new String[] { "id", "fltdcl",
            "intdcl", "print", "assign", "plus", "minus", "$", "inum", "fnum" };

    public final int type;
    public final String val;

    public Token(int type) {
        this(type, "");
    }

    public Token(int type, String val) {
        this.type = type;
        this.val = val;
    }

    public String toString() {
        return "Token type\t" + token2str[type] + "\tval\t" + val;
    }
}

Instead of using ugly arrays, wouldn't it be wiser to modify the constructors to accept strings for a variable typeinstead of integers? Then we could get rid of

    public final static int ID = 0, FLTDCL = 1, INTDCL = 2, PRINT = 3,
            ASSIGN = 4, PLUS = 5, MINUS = 6, EOF = 7, INUM = 8, FNUM = 9;

or is it needed later since using a string instead would be worse?

Answer 1

There are several advantages:

• , ( ) , O (n) , n - . .
• C, ++ Java switch int, .
• .