The following C function should take two strings, and return characters that occur in both strings, without duplicates, and in the order they appear in the first string but doesn't work as it should. Are you able to see the problem?

$//$ inter.c

#include

#include

char$*$ my$\_$strchr$($char$*$ str$,$ char c$)$

$\{$

while $(++$str$)\{$

if $(*$str $==$ c$)\{$

return $($str$)$;

$\}$

if $(*$str $==0)\{$

return $0$;

$\}$

$\}$

return $0$;

$\}$

char $*$my$\_$strnchr$($const char$*$ str$,$ const char c$,$ size$\_$t sz$)$

$\{$

char $*$str$\_$tmp $=0$;

while $($sz$--)\{$

if $(*$str $==$ c$)\{$

str$\_$tmp $=($char $*)$str;

break;

$\}$

str$++$;

$\}$

return str$\_$tmp;

$\}$

char$*$ inter$($char$*$ str$1,$ char$*$ str$2)$

$\{$

char$*$ str $=($char$*)$malloc$($sizeof$($char$)*($sizeof$($str$1)+$ sizeof$($str$2))+1)$;

size$\_$t sz $=0$;

char p$\_$str$1$;

while $(($p$\_$str$1=*$str$1++))$

$\{$

if$($my$\_$strnchr$($str$,$ p$\_$str$1,$ sz$))$

$\{$

continue;

$\}$

if$($my$\_$strchr$($str$2,$ p$\_$str$1))$

$\{$

str$[$sz$++]=$ p$\_$str$1$;

$\}$

$\}$

return str;

$\}$

int main$()$

$\{$

char$*$ test;

test $=$ inter$("$padinton$",$ "paqefwtdjetyiytjneytjoeyjnejeyj"$)$; $//$ "padinto"

$//$ test $=$ inter$("$ddf$6$vewg$64$f$",$ "gtwthgdwthdwfteewhrtag$6$h$4$ffdhsd$")$; $//$ df$6$ewg$4$

printf$("$Result: $\%$s

$",$ test$)$;

return $0$;

$\}$