It's simple, simply output text to STDERR containing the string EOF.
Your input will be none; however, you should output the message to STDERR.
Dyalog 17.0 expects programs to terminate themselves cleanly and will throw an EOF INTERRUPT (and exit with a code 2) if they don't: Try it online!
In contrast, here is the minimal program which does terminate itself cleanly, causing no error (and code 0 upon exit): Try it online!
(
A plain opening bracket is interpreted as the start of a tuple. Just having one bracket is enough to raise an EOF error. Also works with [ and {.
?
When there's no input, an EOF is raised:
Traceback (most recent call last):
File "/opt/keg/Keg.py", line 500, in <module>
exec(header + code + footer)
File "<string>", line 6, in <module>
File "/opt/keg/KegLib.py", line 119, in Input
item = input()
EOFError: EOF when reading a line
Also works with ¿
The following tokens trigger SyntaxError: Unexpected end of input, or a similar message depending on the JS engine.
!
(
+
-
[
{
~
Or to summarize:
for(n = 0; n < 127; n++) {
code = String.fromCharCode(n);
res = false;
try {
eval(code);
}
catch(e) {
res = e.toString() == 'SyntaxError: Unexpected end of input';
}
if(res) {
console.log(code);
}
}
Borland Turbo Assembler will print an "Unexpected end of file" when assembling a zero-byte file.
For the python users; the ones posting one character code, technically that is a SyntaxError which happens to read as an EOFERROR. (FYI, here's an example of all printable single characters that would cause this same error I'm getting a total of 34:)
from string import printable
chars = []
for c in printable:
try: eval(c)
except Exception as e:
if 'EOF' in str(e):
chars += [c]
print(chars)
This prints:
['!', '#', '$', '%', '&', '(', ')', '*', '+', ',', '-', '.', '/', ':', ';', '<', '=', '>', '?', '@', '[', ']', '^', '`', '{', '|', '}', '~', ' ','\t', '\n', '\r', '\x0b', '\x0c']
I'm not sure if raise EOFError would be considered an answer as unfortunately that's the shortest code I can think of to raise a legitimate EOFError in Python 3:
raise EOFError
Without implicitly raising the error in Python 2 you could use this at the expense of an extra byte:
input('\u0004')
raise EOFError is considered invalid because the output contains the exact text EOFError that appears in the source code.
\$\endgroup\$
– A̲̲
Oct 4 at 22:56
EOFError but in py2 the input method does
\$\endgroup\$
– Jab
Oct 6 at 3:45
Each throws: SyntaxError: Unexpected end of input
´
¥
¶
ª
©
«
§
¨
±
µ
÷
Á
Â
Ò
Ó
Test it (Errors are displayed below the output field)
There are also a number of other possibilities, not specific to Japt, that are covered in Arnauld's JS solution, such as:
!
&
|
~
^
1
Run like this: php -r 1
Error: PHP Parse error: syntax error, unexpected end of file in ...
Any other characters apart from ;, #, space and new line should cause a similar error. So PHP probably has ASCII characters count - 4 single byte solutions.
Any of these characters alone will trigger Error: unexpected end of input.
"
'
`
(
{
+
-
!
?
~
Sorry for the edit, misunderstood the question at first :P. We can do [ or ( or { to get unexpected EOF error. In first case, it expects a list, in second a tuple and so on.
[
Perl, 1 byte
(
Try it with
perl -e "("
syntax error at -e line 1, at EOF
Execution of -e aborted due to compilation errors.
RAISERROR('EOF',11,1)
"
.code.tio: line 1: unexpected EOF while looking for matching `"'
.code.tio: line 2: syntax error: unexpected end of file
!
Any of ["!", "(", "*", "+", "-", ":", "[", "{", "~"] will work depending on the environment.
["\"", "%", "'", "/", "`"]. It depends on the exact requirement, though. Some will raise SyntaxError mentioning "end of file" or "end-of-input", but I couldn't find any which includes "EOF".
\$\endgroup\$
– Eric Duminil
Oct 6 at 13:39
"
Not very inspired, but it is the shortest possible in the language.
Outputs Can't find string terminator '"' anywhere before EOF at .code.tio line 1.
All Go files must begin with package [identifier]. The error message is:
can't load package: package main:
src/test.go:1:1: expected 'package', found 'EOF'
e
Old method that's more fun :]
void a()throws Exception{new java.io.DataInputStream(System.in).readInt();}
end of inputorend of fileinstead ofEOF, you should clarify explicitly whether this is allowed. \$\endgroup\$ – Grimmy Oct 4 at 11:14