In latex we can use built-in commands to execute code whether the conditions are true or not.

**Comparing two integers:** `\ifnum\value{num}>n {A} \else {B}\fi`

This code executes A if num>n else B. We can substitute > with < and =.

**If a number is odd:** `\ifodd\value{num} {A}\else {B}\fi`

If num is odd then it executes A else B.

**If with condition:** `\ifthenelse{condition}{A}{B}`

We have to load ifthen package to use this command. If condition are true then it executes A else B.

It is possible to create complex condition with `\( \)`

, `\AND`

, `\OR`

, `\NOT`

.

*For example:* `\ifthenelse{\(\NOT 4<2 \OR 4>11\)\AND\isodd{4}}{A}{B}`

This piece of code writes down "B" on the page. `\NOT 4<2`

is true and `4>11`

is false. If we connect a false and a true statement with "OR" then the result is true. So `\(\NOT 4<2 \OR 4>11\)`

is true. `\isodd{4}`

is false because 4 is even. A false and a true statement connected with "AND" is false, so the output is B.

An example code:

```
\documentclass{article}
\usepackage{ifthen}
\begin{document}
\newcounter{num}
\setcounter{num}{10}
If num$>$100 then the next sentence will be "Num is large." else "Num is small."
Num is \ifnum \value{num}>100 {large} \else {small}.
If num is odd then the next sentence will begin with "Odd" if not then with "Even"
\ifodd \value{num} {Odd} \else {Even} numbers are cool.
If (num$>$3 and (1$<$0 or num$=$10)) is true then the next sentence will be "True." else "False."
\ifthenelse{\value{num}>3\AND\(1<0 \OR \value{num}=10\)}{True.}{False.}
\end{document}
```