How to draw a double head arrow between two points with label

Question

I want to draw an arrow like this <---d--->, alongside a line going from x to y. Thanks.

Answer 1

The answer from marmot was :

\documentclass[tikz,border=3.14mm]{standalone}
\begin{document}
  \begin{tikzpicture}
    \draw[->] (0,0.5) -- (2,0.5);
    \draw[latex-latex] (0,0) -- ++ (2,0) node[midway,fill=white]{label};
  \end{tikzpicture}
\end{document}

But I have a crudely extended this into a command for parameterized use:

\usetikzlibrary{calc}
...
\newcommand{\doublearrowlabel}[5]{
    % accepts a start point, end point, spacing, gradient and label
    \path let \p1=#1 in coordinate (start) at ({\x1 + #3* cos(#4)},{\y1-#3 * sin(#4)});
    \path let \p2=#2 in coordinate (end) at ({\x2 + #3* cos(#4)},{\y2-#3 * sin(#4)});

    \draw[latex-latex]  (start) -- (end) node[midway,fill=white]{#5};
}
...
\draw [->](-0.5,0.8) -- (1,1);
\doublearrowlabel{(-0.5, 0.8)}{(1, 1)}{-5}{75}{First}

\draw [->](-0.5,0.2) -- (-0.8,0.6);
\doublearrowlabel{(-0.5, 0.2)}{(-0.8, 0.6)}{5}{0}{Second}

\draw [->](0.0,-0.3) -- (0.6, 0.3);
\doublearrowlabel{(0.0,-0.3)}{(0.6, 0.3)}{5}{45}{Third}

\draw [->] (0.6, -0.3) -- (0.0,-0.6);
\doublearrowlabel{(0.6, -0.3)}{(0.0,-0.6)}{5}{65}{Fourth}

Answer 2

Simply in math-mode you could use the simple code:

\documentclass[a4paper,12pt]{article}
\usepackage{mathtools}
\begin{document}
$\longleftarrow \mathrm{label}\longrightarrow $
\end{document}

It is possible to use, for example, also as tikz-arrows the tikz-cd package, you can obtained the desidered output.

\documentclass[a4paper,12pt]{article}
\usepackage{mathtools}
\usepackage{tikz-cd}

\begin{document}
\begin{tikzcd}[column sep=2cm]
{} \arrow[r, "\text{label}" description, leftrightarrow] & {}
\end{tikzcd}

\begin{tikzcd}[row sep=2cm]
{} \arrow[d, "\text{label}" description, leftrightarrow]\\
{}
\end{tikzcd}

\begin{tikzcd}[row sep=2cm, column sep=2cm]
{} & \\
   & {} \arrow[lu, "\text{label}" description, leftrightarrow]
\end{tikzcd}

\end{document}