Output or return in Java without using the letter e or digit 5

Question

For this challenge on PCG.SE, one is required to write a function/program that returns/outputs the first N primes. However, the characters with prime code points are not allowed in the program. Two of these characters are `5` and `e`. The code points of either letter contain a `5`. Because of this, `\u{codepoint}` won't work for those two letters. Using escapes, I can remove all prime characters from the code except for the `e` in `return`. I could use `System.out` or `FileDescriptor.out` but both contain the letter `e`. Is there any way to return or output without using an `e` or `5`? For reference here is my code with characters escaped: ``` int[]b(int b\u0029{ int c,d,f[]\u003d{}\u003b for(f\u003dj\u0061v\u0061.util.Arr\u0061ys.copy\u004ff(f,b\u0029\u003bb-->0\u003b\u0029 for(d\u003d0,c\u003d2\u003bf[b]<1\u003bf[b]\u003dd<1?c:f[b],d\u003d0,c\u002b\u002b\u0029 for(int h:f\u0029 d\u003dh>0&&c\u002fh*h\u003d\u003dc?1:d\u003b return f; } ``` Without characters escaped: ``` int[]b(int b…

Accepted Answer

I've found a way to output the prime numbers without using `System.out`, `FileDescriptor.out`, or `return`. My method uses no "prime" characters. This was very tricky, because `e` is all over the place in Java package names, class names, and method names. Also, `S` must be prohibited, because it's number `83` in Unicode, and `83` is prime. Its Unicode escape `\u0053` contains a `5` whose Unicode character `53` is also prime. Here are all the characters we can't use a Unicode escape for under these rules: - `%` (37 is prime, `\u0025` has a `5`) - `5` (53 is prime, `\u0035` has a `5`) - `S` (83 is prime, `\u0053` has a `5`) - `Y` (89 is prime, `\u0059` has a `5`) - `e` (101 is prime, `\u0065` has a `5`) This eliminated: - Any methods such as `toString`, `fromString`, `parseInt`, `valueOf`, and `values`. - `java.beans`, `java.net`, `java.lang.reflect` packages - `Class.forName` - Use of the `new` operator. - Logging frameworks that usually use a `Logger` class that contains `e`. Here are characters for which we can use Unicode escapes: - `)` (41 is prime, `\u0029` is allowed) - `+` (43 is prime, `\u002b` is allowed) - `/` (47 is prime, `\u002f` is allowed) - `;` (59 is prime, `\u003b` is allowed) - `=` (61 is prime, `\u003d` is allowed) - `C` (67 is prime, `\u0043` is allowed) - `G` (71 is prime, `\u0047` is allowed) - `I` (73 is prime, `\u0049` is allowed) - `O` (79 is prime, `\u004f` is allowed) - `a` (97 is prime, `\u0061` is allowed) - `k` (107 is prime, `\u006b` is allowed) - `q` (113 is prime, `\u0071` is allowed) Attempting to generate an exception whose message contains the desired output is the only way to fulfill the requirement in Java. We cannot use a checked exception, because just about all checked exceptions I could find use an `e` in their name, and in every superclass up through `Throwable`. I would be required to use a `throws` clause that included an exception name that contained an `e`. I couldn't `extend` any classes, because `extends` contains `e`s. That leaves unchecked exceptions. The most likely use would be an `IllegalArgumentException` that is created not by this code directly, but by a call to something built-in that throws an `IllegalArgumentException`. - `Enum`s would have helped, except `valueOf` contains an `e`. - `javax.crypto.Mac.getInstance` has an `e`; it throws a checked exception anyway. - `javax.naming.ldap.Rdn.unescapeValue("\b" + stringFormOfOutput)` outputted the list via an exception, but the method has an `e`. - `java.util.UUID.fromString` outputted the list via an exception, but the method has a `S`. This method throws a `DataBindingException` which is unchecked. - `javax.xml.bind.JAXB.unmarshal(stringFormOfOutput, Long.class)` outputted the list via a `DataBindingException`, without an `e`. Now all we have to do is convert the `int[]` to a `String`. String conversion by concatenating the array to `""` doesn't work, because arrays, as objects in Java, don't override `toString()`. `Arrays.toString` is out because of the `S`. We can use `Arrays.asList` to get a `List` out of the data. But `Arrays.asList(f)` gives a `List`, not a `List`, compounding the problem. Changing the type of `f` to `Integer[]` won't work, that has an `e`. Changing the type of `f` to `Long[]` works. The conversion of the array to a `String` is as follows. ``` Long c,d,f[]... ""+Arrays.asList(f) ``` In place of the `return` statement, make the method `void`, and call `unmarshal`. The use of `Long` means a few other adjustments are necessary, such as using `long` literals and `fill`ing the array with zeros instead of the default `null`s. ``` void b(int b){ Long c,d,f[]={}; for(f=java.util.Arrays.copyOf(f,b),Arrays.fill(f,0L);b-->0;) for(d=0L,c=2L;f[b]<1;f[b]=d<1?c:f[b],d=0L,c++) for(long h:f) d=h>0&&c/h*h==c?1:d; javax.xml.bind.JAXB.unmarshal(""+Arrays.asList(f),Long.class); } ``` Escaping the "prime" characters: ``` void b(int b\u0029{ Lon\u0067 c,d,f[]\u003d{}\u003b for(f\u003dj\u0061v\u0061.util.Arr\u0061ys.copy\u004ff(f,b\u0029,Arr\u0061ys.fill(f,0L\u0029\u003bb-->0\u003b\u0029 for(d\u003d0L,c\u003d2L\u003bf[b]<1\u003bf[b]\u003dd<1?c:f[b],d\u003d0L,c\u002b\u002b\u0029 for(lon\u0067 h:f\u0029 d\u003dh>0&&c\u002fh*h\u003d\u003dc?1:d\u003b j\u0061v\u0061x.x\u006dl.bind.JAXB.un\u006d\u0061rsh\u0061l(""\u002bArr\u0061ys.\u0061sList(f\u0029, Lon\u0067.cl\u0061ss\u0029\u003b } ``` This is ugly code, and it probably won't win any code-golfing contests, but it is the only way I can think of in Java to fulfill the requirements. Calling this `b` method with `10` as an argument yields the following output, with `[29, 23, 19, 17, 13, 11, 7, 5, 3, 2]` being the first 10 primes: ``` Exception in thread "main" javax.xml.bind.DataBindingException: javax.xml.bind.UnmarshalException - with linked exception: [java.io.FileNotFoundException: C:\dev\src\misc\[…

Output or return in Java without using the letter e or digit 5

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