Implementation
Perl

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Other implementations
import "os"
fmt.Fprintln(os.Stderr, x, "is negative")
System.err.format("%d is negative\n",x);
eprintln!("{} is negative", x);
#include <stdio.h>
fprintf(stderr,"%d is negative\n",x);
import std.stdio;
stderr.writeln(x, " is negative");
import sys
print(x, "is negative", file=sys.stderr)
import sys
print >>sys.stderr, "%s is negative" % x
writeln(StdErr, Format('%d is negative',[-2]));
import "dart:io";
stderr.write("$x is negative");
warn "#{x} is negative"
$stderr.puts "%d is negative" % x
IO.puts :stderr, "#{x} is negative"
import System.IO (hPutStrLn, stderr)
hPutStrLn stderr (show (x) ++ " is negative")
with Ada.Text_IO;
use Ada.Text_IO;
Put_Line (Standard_Error, Integer'Image (X) & " is negative");
$STDERR = fopen('php://stderr', 'w+');
fwrite($STDERR, "{$x} is negative\n");
io:format(standard_error, "~p is negative~n", [X]).
io.stderr:write(string.format("%d is negative\n",x))
writeln(StdErr , x , ' is negative');
#include <iostream>
std::cerr << x << " is negative" << std::endl;
const util = require("util");
console.error(util.format("%d is negative", x));
console.error(x, "is negative");