in C$++$ Chapter $9$

Use an STL stack to reverse a line of input characters that are read into a string. Your stack should contain the characters of the user's string. Use getline$()$ for input $$ it needs to be part of your C$++$ tool inventory.

NOTE: Do NOT write your own stack class.

A note on getline: Suppose I am doing the following $-$

This program reverses a string using the STL stack

Enter your string of less than $80$ characters followed by an ENTER

a string input

Enter another? $1=$ continue. Anything else to stop

$1$

Enter your string of less than $80$ characters followed by an ENTER

a second string

This code will not work by simply using the following loop:

int go $=1$;

cout $$ "This program reverses a string using the STL stack" $$ endl;

while$($go $==1)\{$

cout $$ "Enter your string of less than $80$ characters followed by an ENTER" $$ endl;

char$*$ s $=($char $*)$malloc$(80)$;

cin.getline$($s$,81,\text{'}$

$\text{'})$;

cout $$ s $$ endl;

cout $$ "Enter another? $1=$ continue. Anything else to stop" $$ endl;

cin $>>$ go;

$\}$

Try it and see what happens! Also note that I never got rid of the memory I allocated with malloc $$ your code must get rid of it$.$ Also, malloc outside the loop for more efficient code.

You must use a getchar$()($part of the cstdio library$)$ after cin $>>$ go;

The reason is that when you enter $1$ you also use the Enter key. This is still in the buffer when you hit getline again! So you will read in $\text{'}$

$\text{'}$

Also note that when you get something off of the STL stack you must use $.$top$()$ to look at it followed by $.$pop$()$ to remove it$.$

Example:

This program reverses a string using the STL stack

Enter your string of less than $80$ characters followed by an Enter

m&m cheeto mayo

oyam oteehc m&m

Enter another? $1=$ continue. Anything else to stop

$1$

Enter your string of less than $80$ characters followed by an Enter

celery lettuce apple

elppa ecuttel yrelec

Enter another? $1=$ continue. Anything else to stop

$0$

Press any key to continue $...$

The reason is that when you enter $1$ you also use the Enter key. This is still in the buffer when you hit getline

again! So you will read in $\text{'}$In$\text{'}$

Also note that when you get something off of the STL stack you must use $.$top$()$ to look at it followed by $.$pop$()$

remove it$.$

Example:

This program reverses a string using the STL stack

Enter your string of less than $80$ characters followed by an Enter

m&m cheeto mayo

oyam oteehc m&m

Enter another? $1=$ continue. Anything else to stop

$1$

Enter your string of less than $80$ characters followed by an Enter

celery lettuce apple

elppa ecuttel yrelec

Enter another? $1=$ continue. Anything else to stop

$0$

Press any key to continue $...$