Help for this page

Select Code to Download

Select or download this

print(
 (length(join('',map { $mystring =~ /$_/ ? '' : 'X' } @a)) 
 ?   'not ' 
 :   ''),
 "all letters occur\n");

Select or download this
```
index($mystring,$_) < 0 ? 'X' : ''
```