Use of uninitialized value at?

[vivekvp]

Hello

I am using the DBI to grab some data from a database. Some of the database table fields are NULL. I am receiving this error

Use of uninitialized value at /test/getform.cgi line 47


Here is the code

43  $sth=$dbh->prepare("select * from names where id=?");
44  $sth->execute($poreq);                                      
45  my @ar = $sth->fetchrow_array();                            
46          foreach $ar (@ar) {                                 
47                  print "$ar \n";                             
48          }                                                   
49  $sth->finish;

How do I prevent the error without dropping the perl -w option? Or do I need to put in an code to check the value of $ar in the foreach loop?


Many thank yous...

He who laughs last, doesn't get the joke.

[chromatic]

In versions 5.6 and later, you can use no warnings 'uninitialized' to suppress that error. In prior versions, you can localize a warnings handler ($SIG{__WARN__}) to suppress that error. Otherwise, you have several options.

• Use a map block to set each element in the array to a null string if it's not defined.
• Skip undefined elements in the loop.
• Turn undefined elements into blank strings within the loop.

[grantm]

And in versions before 5.6 you can use the $^W global. eg:

  {
    local($^W) = 0;    # suppress warnings
    ... your code here ...
  }

[kabel]

one common idiom: defined $val or $val = ""; then $val is at least defined, and no warning appears.

HTH

[blakem]

Or, since we want to apply this rule to a list:

$_ = '' for grep !defined, @arr;

-Blake

[dpuu]

Another alternative is to "catch" the warning:

  local $SIG{__WARN__} = sub {
    warn @_ unless $_[0] =~ /uninitialised/;
  };

--Dave

[BrowserUk]

Done better (and correctly) above.

[Chmrr]

..as well as prevent seeing any columns that are zero, the empty string, and so on. print "$ar \n" if defined $ar; is probably the way to go in this case.

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'