Example $2$: Pointers.

#include

using namespace std;

void increment$\_$all$($int$*$ start, int$*$ stop$)\{$

int$*$ current $=$ start;

while $($current $!=$ stop$)\{$

$++(*$current$)$;

$++$current;

$\}$

$\}$

void print$\_$all$($const int$*$ start, const int$*$ stop$)\{$

const int$*$ current $=$ start;

while $($current $!=$ stop$)\{$

cout $<<*$current $<<\text{'}$

$\text{'}$;

$++$current;

$\}$

$\}$

int main$()\{$

int numbers$[]=\{10,20,30\}$;

increment$\_$all$($numbers$,$ numbers $+3)$;

print$\_$all$($numbers$,$ numbers $+3)$;

return $0$;

$\}$

$\{//$Assume that the address of the variable a $=0015$FAA$0$

int a;

int $*$aPtr;

a $=7$;

aPtr $=$ &a;

cout $<<$ &a $<<$ endl;

cout $<<$ aPtr $<<$ endl;

cout $<<$ a $<<$ endl;

cout $<<*$aPtr $<<$ endl;

cout $<<$ &$*$aPtr $<<$ endl;

cout $<<*$&aPtr $<<$ endl;

return $0$;$\}$

$2$ #include

using namespace std;

int main $()$

$\{$ int num$1,$ num$2$;

int $*$mypointer;

mypointer $=$ &num$1$;

$*$mypointer $=10$;

mypointer $=$ &num$2$;

$*$mypointer $=20$;

cout $<<$ "firstvalue is $"<<$ num$1<<$ endl;

cout $<<$ "secondvalue is $"<<$ num$2<<$ endl;

return $0$;$\}$

$3$ #include

using namespace std;

int main $()$

$\{$

int firstvalue $=5,$ secondvalue $=15$;

int $*$p$1,*$p$2$;

p$1=$ &firstvalue;

p$2=$ &secondvalue;

$*$p$1=10$;

$*$p$2=*$p$1$;

p$1=$ p$2$;

$*$p$1=20$;

cout $<<$ "firstvalue is $"<<$ firstvalue $<<$ endl;

cout $<<$ "secondvalue is $"<<$ secondvalue $<<$ endl;

return $0$;

$\}$

$4$ #include

using namespace std;

void double$\_$it$\_1($int $*$p$)$

$\{$

$*$p $=*$p $*2$;

$\}$

void double$\_$it$\_2($int n$)$

$\{$

n $=$ n$*2$;

$\}$

int main$()\{$

int var $=10$;

int $*$pvar $=$ &var;

cout $<<*$pvar $<$

using namespace std;

int main$()\{$

int $*$pc$,$ c;

c $=5$;

cout $<<$ "Address of c $($&c$)$: $"<<$ &c $<<$ endl;

cout $<<$ "Value of c $($c$)$: $"<<$ c $<<$ endl $<<$ endl;

pc $=$ &c; $//$ Pointer pc holds the memory address of variable c

cout $<<$ "Address that pointer pc holds $($pc$)$: $"<<$ pc $<<$ endl;

cout $<<$ "Content of the address pointer pc holds $(*$pc$)$: $"<<*$pc $<<$ endl $<<$ endl;

c $=11$; $//$ The content inside memory address &c is changed from $5$ to $11.$

cout $<<$ "Address pointer pc holds $($pc$)$: $"<<$ pc $<<$ endl;

cout $<<$ "Content of the address pointer pc holds $(*$pc$)$: $"<<*$pc $<<$ endl $<<$ endl;

$*$pc $=2$;

cout $<<$ "Address of c $($&c$)$: $"<<$ &c $<<$ endl;

cout $<<$ "Value of c $($c$)$: $"<<$ c $<<$ endl $<<$ endl;

return $0$;

$\}$

Example $2$: Pointers.

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$//$ pointers as arguments:

#include

using namespace std;

void increment$\_$all $($int$*$ start, int$*$ stop$)$

$\{$

int $*$ current $=$ start;

while $($current $!=$ stop$)\{$

$++(*$current$)$; $//$ increment value pointed

$++$current; $//$ increment pointer

$\}$

$\}$

void print$\_$all $($const int$*$ start, const int$*$ stop$)$

$\{$

const int $*$ current $=$ start;

while $($current $!=$ stop$)\{$

cout $<<*$current $<<\text{'}$

$\text{'}$;

$++$current; $//$ increment pointer

$\}$

$\}$

int main $()$

$\{$

int numbers$[]=\{10,20,30\}$;

increment$\_$all $($numbers$,$numbers$+3)$;

print$\_$all $($numbers$,$numbers$+3)$;

return $0$;

$\}$

Example $3$: void Pointers

$//$ increaser

#include

using namespace std;

void increase $($void$*$ data, int psize$)$

$\{$

if $($ psize $==$ sizeof$($char$))$

$\{$ char$*$ pchar; pchar$=($char$*)$data; $++(*$pchar$)$; $\}$

else if $($psize $==$ sizeof$($int$))$

$\{$ int$*$ pint; pint$=($int$*)$data; $++(*$pint$)$; $\}$

$\}$

int main $()$

$\{$

char a $=\text{'}$x$\text{'}$;

int b $=1602$;

increase $($&a$,$sizeof$($a$))$;

increase $($&b$,$sizeof$($b$))$;

cout $<<$ a $<<","<<$ b $<<\text{'}$

$\text{'}$;

return $0$;

$\}$

Example $4$: Pointers to functions

$//$ pointer to functions

#include

using namespace std;

int addition $($int a$,$ int b$)$

$\{$ return $($a$+$b$)$; $\}$

int subtraction $($int a$,$ int b$)$

$\{$ return $($a$-$b$)$; $\}$

int operation $($int x$,$ int y$,$ int $(*$functocall$)($int$,$int$))$

$\{$

int g;

g $=(*$functocall$)($x$,$y$)$;

return $($g$)$;

$\}$

int main $()$

$\{$

int m$,$n;

int $(*$minus$)($int$,$int$)=$ subtraction;

m $=$ operation $(7,5,$ addition$)$;

n $=$ operation $(20,$ m$,$ minus$)$;

cout $<$

using namespace std;

const int MAX $=3$;

int main $()\{$

int var$[$MAX$]=\{10,100,200\}$;

int $*$ptr$[$MAX$]$;

for $($int i $=0$; i $<$ MAX; i$++)\{$

ptr$[$i$]=$ &var$[$i$]$; $//$ assign the address of integer.

$\}$

for $($int i $=0$; i $<$ MAX; i$++)\{$

cout $<<$ "Value of var$["<<$ i $<<"]="$;

cout $<<*$ptr$[$i$]<<$ endl;

$\}$

return $0$;

$\}$

Example $6$: Pointer Array

#include

using namespace std;

const int MAX $=4$;

int main $()\{$

char $*$names$[$MAX$]=\{$

"Zara Ali",

"Hina Ali",

"Nuha Ali",

"Sara Ali",

$\}$;

for $($int i $=0$; i $<$ MAX; i$++)\{$

cout $<<$ "Value of names$["<<$ i $<<"]="$;

cout $<<$ names$[$i$]<<$ endl;