$.$ Scrutinise the code shown in Figure Q$3$ on page $7.$ The numbers at the beginning of

each line are provided for ease of reference and are not part of the program.

$($a$)$ The operators $*$ and & have different meanings depending on whether they are

used in a declaration or an expression. Using diagrams, explain the meaning of

$*$ used in the each of the following lines:

int$*$ ip $\{$ new int $\}$;

$*$ip $=1$;

$[2]$

$($b$)$ Using English words, write out the full type of the variable vp$1$ which is declared

on line $22$ of Figure Q$3.[2]$

$($c$)$ Using English words, write out the full type of the arguments of the template

function zipvectors declared on line $6.[2]$

$($d$)$ Explain why the unique pointers themselves cannot be passed as arguments,

but must be passed by reference. $[2]$

$($e$)$ Explain what the function zipvectors does. Include the types of the arguments

and return value. Hence deduce the program$$s expected output. $[5]$

$($f$)$ the author of the function made a great effort to avoid passing vectors as

arguments. Explain why. $[2]$

$($g$)$ The author made no effort to avoid returning a vector from the function. Explain

why. $[2]$

$($h$)$ How could the type of the arguments be changed to avoid the use of pointers

but without compromise in function, safety or efficiency? $[2]$

When line $25$ is changed to set $*$vp$2$ to $\{10,20\}$ and the program is recompiled,

the following output is produced:

terminate called after throwing an instance of

$\text{'}$std::out$\_$of$\_$range'

what$()$: vector::$\_$M$\_$range$\_$check:

$\_\_$n $($which is $2)>=$ this$->$size$()($which is $2)$

Aborted $($core dumped$)$

$($i$)$ Why did the change result in an exception being thrown? $[2]$

$($j$)$ Decide on a desired behaviour when the arguments are vectors of differing length,

and write out a revised version of zipvectors incorporating the improvements

you suggested in Q$3$h$.[4]$

Page $6$ of $13/$OVER

$1$ #include

$2$ #include

$3$ #include

$4$

$5$ template

$6$ std::vector zipvectors$($

$7$ std::unique$\_$ptr$>$ const& vptr$1,$

$8$ std::unique$\_$ptr$>$ const& vptr$2$

$9)$

$10\{$

$11$ std::vector result;

$12$ result.reserve$(2*$vptr$1->$size$())$;

$13$ for $($int i $\{0\}$ ; i $<$ vptr$1->$size$()$ ; i$++)\{$

$14$ result.push$\_$back$($vptr$1->$at$($i$))$;

$15$ result.push$\_$back$($vptr$2->$at$($i$))$;

$16\}$

$17$ return result;

$18\}$

$19$

$20$ int main$()$

$21\{$

$22$ auto vp$1\{$ std::make$\_$unique$>()\}$;

$23*$vp$1=\{-1,-2,-3,-4\}$;

$24$ auto vp$2\{$ std::make$\_$unique$>()\}$;

$25*$vp$2=\{2,4,6,8\}$;

$26$

$27$ for $($const int& i : zipvectors$($vp$1,$ vp$2))$

$28$ std::cout $<<$ i $<<\text{'}\backslash$t$\text{'}$;

$29$ std::cout $<<$ std::endl;

$30$

$31$ return $0$;

$32\}$