$($C$++$assignment$)$ a calculator program. very important college assignment I'll fail my class if I dont get a good grade for this. it has $2$ starting codes. please dont change the starting codes and just complete them. Below is the claculator.cpp and the pictures are main.cpp$.$

#include

$/*$

$*$ THIS IS A HELPER FUNCTION. YOU AREN'T REQUIRED TO USE IT$,$ AND YOU CAN

$*$ MODIFY IT IF YOU WANT, BUT I STRONGLY RECOMMEND THAT YOU USE IT AS$-$IS$.$

$*$ YOU MAY FIND IT VERY HELPFUL.

$*$ Function: is$\_$number

$*$ Description: Determines whether a given string holds a valid numeric value

$*$ Returns: True if the given string holds a valid numeric value, or false

$*$ otherwise. If this function returns true, it's safe to use std::stod$()$

$*$ on the string to convert it to a number $($double$)$ afterwards. Otherwise,

$*$ the given string does not contain a valid numeric value, and attempting

$*$ to use std::stod$()$ on the string may crash your program.

$*/$

bool is$\_$number$($std::string str$)\{$

$//$ A valid number must contain at least one digit and at most one

$//$ decimal point

int num$\_$digits $=0$;

int num$\_$points $=0$;

for $($int i $=0$; i $$ str$.$length$()$; i$++)\{$

bool is$\_$point $=$ str$.$at$($i$)==\text{'}.\text{'}$;

$//$ A negative sign is a dash at the beginning of the string

bool is$\_$negative$\_$sign $=$ str$.$at$($i$)==\text{'}-\text{'}$ && i $==0$;

bool is$\_$number $=$ str$.$at$($i$)>=\text{'}0\text{'}$ && str$.$at$($i;

if $($is$\_$point$)\{$

$//$ If the character is a decimal point, increment

$//$ the number of points found, and return false if

$//$ it's greater than $1$

num$\_$points$++$;

if $($num$\_$points $>1)\{$

return false;

$\}$

$\}$

if $($is$\_$number$)\{$

$//$ If the character is a digit, increment the number of

$//$ digits found

num$\_$digits$++$;

$\}$

$//$ If the character isn't any of the three valid possibilities,

$//$ return false, immediately ending the function

if $(!$is$\_$point && $!$is$\_$negative$\_$sign && $!$is$\_$number$)\{$

return false;

$\}$

$\}$

$//$ Return true only if at least one digit was found

return num$\_$digits $>0$;

$\}$

$//$ TODO Write other functions as you see fit.

$/*$

$*$ THIS IS A REQUIRED FUNCTION. YOU MAY NOT ALTER ITS HEADER $($NAME$,$ PARAMETERS,

$*$ OR RETURN TYPE$)$ IN ANY WAY.

$*$ Function: is$\_$valid$\_$expression

$*$ Description: Determines whether a given string holds a valid arithmetic

$*$ expression, as defined in the assignment document.

$*$ Parameters:

$*$ expression $($std::string$)$: A string holding the expression to be checked

$*$ for validity.

$*$ Returns: True if the given string holds a valid arithmetic expression, or

$*$ false otherwise.

$*$

$*$ For example, is$\_$valid$\_$expression$("1+3*4")$ should return true, but

$*$ is$\_$valid$\_$expression$("1+3*4")$ should return false $($notice the lack of spaces;

$*$ see the assignment document for an explanation of what constitutes a valid

$*$ arithmetic expression for this assignment$).$

$*/$

bool is$\_$valid$\_$expression$($std::string expression$)\{$

$//$ TODO Complete this function. You may create other functions above and have

$//$ this function call them, if you'd like $($you probably should for the sake

$//$ of the course's style guidelines$)$

$//$ TODO Remove the below return statement. It's a placeholder just to get

$//$ the starter code to compile without warnings and run without undefined

$//$ behavior.

return false;

$\}$

$/*$

$*$ THIS IS A REQUIRED FUNCTION. YOU MAY NOT ALTER ITS HEADER $($NAME$,$ PARAMETERS,

$*$ OR RETURN TYPE$)$ IN ANY WAY.

$*$ Function: compute$\_$value

$*$ Description: Computes and returns the value of the given arithmetic

$*$ expression. This function should ASSUME that the given string is indeed

$*$ a valid arithmetic expression. That is$,$ your program should check whether

$*$ a string contains a valid arithmetic expression $($e$.$g$.,$ using your

$*$ is$\_$valid$\_$expression function$)$ BEFORE passing it into this function.

$*$ Parameters:

$*$ expression $($std::string$)$: A string holding the arithmetic expression

$*$ to be evaluated.

$*$ Returns $($double$)$: The value of the given arithmetic expression, computed

$*$ according to the rules described in the assignment document

$*$

$*$ For example: compute$\_$value$("1+3*4")$ should return $16,$ assuming you don't

$*$ complete the order$-$of$-$operations extra credit.

$*/$

double compute$\_$value$($std::string expression$)\{$

$//$ TODO Complete this function. You may create other functions above and have

$//$ this function call them, if you'd like $($you probably should for the sake

$//$ of the course's style guidelines$)$

$//$ TODO Remove the below return statement. It's a placeholder just to get

$//$ the starter code to compile without warnings and run without undefined

$//$ behavior.

return $0$;

$\}$

Also I wasnt allowed to use AI$.$