Output the ASCII tilde character

Question

The internet is awash with questions and answers for producing a nice looking tilde. But my goal is to produce output (PDF, let's say) from which one can copy-paste into another application and get the same result as typing the ~ character from the keyboard. I don't care how it looks, I only care if it can be copy-pasted.

This is not a question about how to display a tilde symbol. \textasciitilde, \~{}, and $\sim$ all do that. However, the first two generate (UTF-8)CC83 = U+0303 = "combining tilde" and the last generates (UTF-8)E288BC = U+223C from the mathematical operators table. (As determined by pasting into emacs and using hexl-mode.)

It seems as though there should be a font-independent solution, considering that ~ is in ASCII (U+7E, to be specific), and therefore should be present in every font. The answer may be font (encoding) dependent, since ~ is not a required glyph for general text encodings (LaTeX font encodings section 3.1). But all (La)TeX code I've found (including the url package) generate higher UNICODE characters, so it would be surprising if an ASCII character were impossible.

Answer 1

The general statement that being in ascii means it should work is false see

1 < 2 

in OT1 for a clearer example. For ~ the character in slot 7E of OT1 is the tilde accent so ̃ not ~ which is why \~{} putting a tilde accent on nothing is an approximation and is the definition of \textasciitilde in OT1

You can use the accsupp package to provide a real ~ for cut and paste around a visual \~{}

\documentclass{article}
\usepackage{accsupp}
\begin{document}
[\textasciitilde] [\BeginAccSupp{method=hex,unicode,ActualText=007E}\textasciitilde\EndAccSupp{}]
\end{document}

makes

If I cut and paste to

https://w3c.github.io/xml-entities/unicode-names.html?%5B%CB%9C%5D%20%5B~%5D%0A

I get

Result:
U+005b LEFT SQUARE BRACKET     [ [ \lbrack [
  U+02dc SMALL TILDE     ˜ ˜ \texttildelow
  U+005d RIGHT SQUARE BRACKET     ] ] \rbrack ]
  U+0020 SPACE     \space
  U+005b LEFT SQUARE BRACKET     [ [ \lbrack [
  U+007e TILDE     \textasciitilde
  U+005d RIGHT SQUARE BRACKET     ] ] \rbrack ]

showing the second one is a ~

Or better (via Ulrike) use \pdfglyphtounicode

\documentclass{article}
\pdfglyphtounicode{tilde}{007E}
\begin{document}
[\textasciitilde]
\end{document}

Note this is only an issue in the 7-bit OT1 encoding, if you use any reasonable encoding such as T1 in pdflatex or TU (Unicode) in lualatex, then \textasciitilde will work by default

Answer 2

If \~{} did not work, try this. Works for me:

In Preamble,

\makeatletter
\edef\realtilde{\expandafter\@gobble\string\~}
\makeatother

In document body, examples:

Hello\realtilde World % Prints without space.
Hello \realtilde\space World % Prints with both spaces.

I do not recall where I got the macro definition. Years ago.