#include

using namespace std;

$//$functions prototypes

double getPositive$($

dblVal $)$;

getRectangleNSquareArea$($ double l$,$ double w $)$;

getTriangleArea$($ double b$,$ double h $)$;

double getCircleArea$($

r $)$ ;

int main$()\{$

char input;

$\{$

cout $<<"------------------------------$

$"$;

cout $<<$ "Welcome to a geometry calculator!

$"$;

cout $<<$ "Insert $\text{'}$R$\text{'}$ for Rectangle.

$"$;

cout $<<$ "Insert $\text{'}$S$\text{'}$ for Square.

$"$;

cout $<<$ "Insert $\text{'}$T$\text{'}$ for Triangle.

$"$;

cout $<<$ "Insert $\text{'}$C$\text{'}$ for Circle.

$"$;

cout $<<"$

Insert $\text{'}$Y$\text{'}$ to continue.

$"$;

cout $<<$ "Insert $\text{'}$N$\text{'}$ to finish the program.

$"$;

cout $<<"------------------------------$

$"$;

cout $<<$ "Please select your choice

$"$;

cout $<<$ "Input: $"$;

cin $>>$ input;

double value$1=0$;

double value$2=0$;

double area $=0$;

$($

$)\{$

case $\text{'}$r$\text{'}$:$//$ accept a lower case

case $\text{'}$R$\text{'}$:

cout $<<$ "RECTANGLE $-$ Solve for area

$"$;

cout $<<$ "Length: $"$;

cin $>>$ value$1$;

value$1=$ getPositive$($ value$1)$;

cout $<<$ "Width: $"$;

cin $>>$ value$2$;

value$2=$

$($ value$2)$;

area $=$

$($ value$1,$ value$2)$;

cout $<<$ "Area $="<<$ area $<<$ endl;

break;

case $\text{'}$s$\text{'}$:

case $\text{'}$S$\text{'}$:

cout $<<$ "SQUARE $-$ Solve for area

$"$;

cout $<<$ "Side: $"$;

cin $>>$ value$1$;

value$1=$

$($ value$1)$;

area $=$

$($

$,$

$)$;

cout $<<$ "Area $="<<$ area $<<$ endl;

break;

case $\text{'}$t$\text{'}$:

case $\text{'}$T$\text{'}$:

cout $<<$ "TRIANGLE $-$ Solve for area

$"$;

cout $<<$ "Base: $"$;

cin $>>$ value$1$;

value$1=$

$($ value$1)$;

cout $<<$ "Height: $"$;

cin $>>$ value$2$;

value$2=$ getPositive$($ value$2)$;

area $=$

$($value$1,$ value$2)$;

cout $<<$ "Area $="<<$ area $<<$ endl;

break;

case $\text{'}$c$\text{'}$:

case $\text{'}$C$\text{'}$:

cout $<<$ "CIRCLE $-$ Solve for area

$"$;

cout $<<$ "Radius: $"$;

cin $>>$ value$1$;

value$1=$

$($ value$1)$;

area $=$

$($ value$1)$;

cout $<<$ "Area $="<<$ area $<<$ endl;

break;

case $\text{'}$n$\text{'}$: case $\text{'}$N$\text{'}$: case $\text{'}$y$\text{'}$: case $\text{'}$Y$\text{'}$: $//$n$,$N$,$y$,$Y are valid input

break;

default:

cout $<<$ "INVALID INPUT $-$ Try again!

$"$;

$\}$

$\}$

$(($input $!=\text{'}$N$\text{'})$

$($input $!=\text{'}$n$\text{'}))$

cout $<<"$

$*****************************************$

$"$;

cout $<<"*$ KEEP CALM AND CODE ON AND BE SAFE! $*"$;

cout $<<"$

$*****************************************$

$"$;

return $0$;

$\}$

$//$functions implementation

double

$($

dblVal $)\{$

while$($

$0)\{$

cout $<<$ "Try again!

A positive number please: $"$;

cin $>>$ dblVal;

$\}$

dblVal;

$\}$

double

$($ double l$,$ double w $)\{$

return l $*$

;

$\}$

double

$($ double b$,$ double h $)\{$

return $($b $*$ h$)/2$;

$\}$

double

$($ double r $)\{$

const double PI $=3\mathrm{.}14$;

return

$*($r $*$ r$)$;