• JS

throw new Error('x is invalid');

• C

enum {
    E_OK,
    E_OUT_OF_RANGE
};

int square(int x, int *result) {
    if (x > 1073741823) {
        return E_OUT_OF_RANGE;
    }
    *result = x*x;
    return E_OK;
}

• C++

throw domain_error("oops!");

• C#

throw new ArgumentException(nameof(×));

• D

throw new Exception("invalid value for x (%s) in '%s'".format(x, __PRETTY_FUNCTION__));

• D

void foo(int x)
in
{
    assert(x != 0, "wrong value for x");
}
body
{
    // function
}

• Erlang

error(badarg).

• Fortran

  if (x > largest_value) error stop "Illegal value in function."

• Go

return nil, fmt.Errorf("invalid value for x: %v", x)

• Groovy

throw new IllegalArgumentException("Invalid value for x: $x")

• Haskell

sqrt' :: Int -> Either String Int
sqrt' x | x < 0 = Left "Invalid argument"
sqrt' x         = Right (sqrt x)

• Java

void f(int x) {
    Objects.checkIndex(x, 123);
}

• Java

<T> void f(T x) throws Exception {
    if (x != value) throw new Exception();
}

• Java

<T> void f(T x) {
    Objects.requireNonNull(x);
}

• Java

throw new IllegalArgumentException("Invalid value for x:" + x);

• Lua

error("Invalid argument x")

• Lua

return nil, "Invalid argument x"

• PHP

throw new \InvalidArgumentException($x . ' is invalid.');

• Pascal

Raise EInvalidArgument.CreatFmt('Invalid value: %d',[x]);

• Perl

die "Invalid argument $x";

• Python

raise ValueError("x is invalid")

• Ruby

raise ArgumentError, "invalid value #{x}."

• Rust

enum CustomError { InvalidAnswer }

fn do_stuff(x: i32) -> Result<i32, CustomError> {
    if x != 42 {
        Err(CustomError::InvalidAnswer)
    } else {
        Ok(x)
    }
}