• Smalltalk

OS.Stderr 
  nextPutAll: x asString;
  nextPutAll: ' is negative';
  nextPut: Character cr.

• Ada

Put_Line (Standard_Error, Integer'Image (X) & " is negative");

• C

fprintf(stderr,"%d is negative\n",x);

• Clojure

(binding [*out* *err*]
  (println (str x " is negative")))

• C++

std::cerr << x << " is negative\n";

• C++

int main(){
	int x = -2;
	std::cerr << x <<" is negative\n";
}

• C#

Console.Error.WriteLine($"{x} is negative");

• D

stderr.writeln(x, " is negative");

• Dart

stderr.write("$x is negative");

• Elixir

IO.puts :stderr, "#{x} is negative"

• Erlang

io:format(standard_error, "~p is negative~n", [X]).

• Fortran

program write_to_stderr
   use iso_fortran_env, only : stderr=>ERROR_UNIT   
   implicit none
   integer :: x=-2
   write(stderr,'(i0," is negative")') x
end program write_to_stderr

• Go

fmt.Fprintln(os.Stderr, x, "is negative")

• Haskell

hPutStrLn stderr (show (x) ++ " is negative")

• JS

console.error(util.format("%d is negative", x));

• JS

console.error(`${x} is negative`);

• JS

console.error(x, "is negative");

• Java

System.err.printf("%d is negative", x);

• Java

System.err.format("%d is negative\n",x);

• Kotlin

System.err.println("$x is negative")

• Lisp

(format *error-output*
        "~a is negative"
        x)

• Lua

io.stderr:write(string.format("%d is negative\n",x))

• Obj-C

NSLog(@"%d is negative",x)

• PHP

fwrite(STDERR, "{$x} is negative\n");

• Pascal

writeln(StdErr, Format('%d is negative',[-2]));

• Pascal

writeln(StdErr , x , ' is negative');

• Perl

print STDERR "$x is negative";

• Python

print(x, "is negative", file=sys.stderr)

• Ruby

warn "#{x} is negative"
$stderr.puts "%d is negative" % x

• Rust

eprintln!("{} is negative", x);

• Scala

System.err.println(s"$x is negative")