For the underscore, the following works:
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage[ngerman]{babel}
\catcode`\_=\active
\protected\def_{\begingroup\itshape\aftergroup\/\let_\endgroup}
\begin{document}
Hello \textit{World!} How are you?
Hello _World!_ How are _you?
I'm fine._ And you?
_I'm fine, too.
Glad to hear that._
\end{document}
However, it is a bit crazy and unstable. If you want to use it only for short texts (not spanning multiple paragraphs), the following would be better. (It doesn't work in the above example, since there we span multiple pagraphs. In real, it will throw an error if you put odd number of _
in one paragraph.)
\catcode`\_=\active
\protected\def_#1_{\textit{#1}}
You can use the same ideas for the star. The problem is, that \section*{Text}
will suddenly stop working. Variant 1:
\catcode`\*=\active
\protected\def*{\begingroup\bfseries\let*\endgroup}
Variant 2:
\catcode`\*=\active
\protected\def*#1*{\textbf{#1}}
If you don't use math at all, just use ^
instead of *
and it should be ok.
How does it work: The primitive macro \catcode
makes _
\active
so that we can define it as any other command.
In Variant 1, we define it to (1) start a group (2) start italic text (3) add italic correction to the end of the italic text (4) make the one next _
end the group we started. By the end of the group, the re-definition of _
is forgotten so another _
will again start an italic text.
The Variant 2 is even simpler: When _
is found, a second _
is looked for, end everything inbetween is put into \textit
.
The \protected
directive makes sure that _
is written as _
in the auxiliary files, which is necessary for it to behave correctly.
For centering use the environment center
. Use the mathmode only if needed. However, there are some errors in your code. A working one:
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage[a4paper, total={6in, 8in}]{geometry}
\setlength\parindent{0pt}
\usepackage{xcolor}
\usepackage{setspace}
\begin{document}
\begin{center}
\textbf {User schema}
\end{center}
\setstretch{1.5}
\textbf {ID : } \textcolor{red}{ObjectId }- Id do registro \\
\textbf {Name: } \textcolor{red}{ String } - Name co usuario \\
\textbf {date: } \textcolor{red}{ Date } - Date de Cadastro \\
\textbf {ren\_date: } \textcolor{red}{ Date } - Data de
\textbf {email: } \textcolor{red}{ String } - Lorem ipsum dolorsitamet, consecteturadipisicingelit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minimveniam, exercitationullamcolaborisnisi ut aliquipexeacommodoconsequat. Duisautereprehenderit in voluptatevelit esse cillumdolore eu fugiatnullapariatur. Occaecatcupidatat non proident, sunt in culpa quiofficiadeseruntmollit.
\[
\text{accesslog: \textcolor{red}{ Array }}
\left(
\begin{array}{@{}ll}
\left\{\begin{tabular}{l}
\textbf{date}: \textcolor{red}{string} Data -- da ocorrncia.\\
\textbf{ObjectId}: \textcolor{red}{Usuário} -- que executou.\\
\textbf{action}: \textcolor{red}{String} -- Aço Executada.\\
\end{tabular}\right.\\
~\\
\left\{
\begin{tabular}{l}
\textbf{date}: \textcolor{red}{string} Data -- da ocorrncia.\\
\textbf{ObjectId}: \textcolor{red}{Usuário} -- que executou.\\
\textbf{action}: \textcolor{red}{String} -- Aço Executada.\\
\end{tabular}\right.
\end{array}
\right.
\]
\textbf {group\_id : } \textcolor{red}{ ObjectId } - Id do grupo.
\end{document}

Hyperlinks can be set with \label{..}
and \href{text}{link}
. I do not really understand what you mean by "email". In general it is set with \url
.
Best Answer
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Here is the output.