LaTeX symbol for “\rightarrow” with “\triangleq” und “\leftarrow” with “\triangleq”

Question

How can I create those two symbols in LaTeX?

I am reading my old post but I can´t, I would do as like as Steven B. Segletes has answered

Answer 1

simply replace leftright in this answer by left and right, respectively (you should preferably use mathrel, thanks @egreg):

\documentclass{article}
\usepackage{amsmath}
\usepackage{amssymb}
\newcommand{\leftrightarrowtriangleqbin}{\mathbin{\overset\triangleq\leftrightarrow}}
\newcommand{\leftrightarrowtriangleqrel}{\mathrel{\overset\triangleq\leftrightarrow}}

\newcommand{\rightarrowtriangleqbin}{\mathbin{\overset\triangleq\rightarrow}}
\newcommand{\rightarrowtriangleqrel}{\mathrel{\overset\triangleq\rightarrow}}

\begin{document}
$S \leftrightarrowtriangleqbin T$\\
$S \leftrightarrowtriangleqrel T$\\
$S \rightarrowtriangleqbin T$\\
$S \rightarrowtriangleqrel T$
\end{document}

EDIT: since you asked for an adaption of the other solution (which was not the accepted answer)

\documentclass{article}
\usepackage[usestackEOL]{stackengine}
\usepackage{amssymb}
\def\symA{\mathrel{\stackon[-0.8pt]{\longrightarrow}%
  {\scriptstyle\triangleq}}}
\def\symB{\mathrel{\stackon[.7pt]{\longrightarrow}%
  {\setstackgap{S}{0pt}\Shortstack{%
  \scriptscriptstyle\triangle\\\rule[.8pt]{6pt}{0.25pt}\\\rule{8pt}{.25pt}}}}}
\def\symC{\mathrel{\stackon[-0.8pt]{\longleftarrow}%
        {\scriptstyle\triangleq}}}
\def\symD{\mathrel{\stackon[.7pt]{\longleftarrow}%
        {\setstackgap{S}{0pt}\Shortstack{%
                \scriptscriptstyle\triangle\\\rule[.8pt]{6pt}{0.25pt}\\\rule{8pt}{.25pt}}}}}
\stackMath
\begin{document}
$A \symA B \symB C \symC D \symD E$
\end{document}