my @chk_acc = split('-',@account);
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my @chk_acc = split('-',4);
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Also, use strict and warnings because warnings will give you other useful info.

perltidy can help the indenting-impaired :)

If you wish to reorder your output you need to reorder your data. For that you can collect data into data structures as you go through the array. Then process the data structures at the end.

Here are some further points of potential confusion that I see in your code.

• You are passing @account where a scalar is expected. My map statement is more likely to do what you want.
• You are putting array elements in $checked then not specifying what to chomp, so it chomps $_. Nothing is in $_ so that is useless.
• 0-9 match \w so your regular expression will match 7 digit numbers. This is may surprise you at some point. Hence my changed regular expression.
• The i and g modifiers to your regular expression are doing nothing and hence may surprise you.
• Your code comments suggest that you expect multiple elements to be output together when you are printing them one element at a time. If so you have a lot of confusion around what iteration is and how it works. (Which fits with my understanding of your initial question.)

my @account = qw(
    34765-22333-333489-99867-22340-23456-3229 XLM8876 AMP7765 WQP22349
);

my @account_starting_with_digit;
my @account_starting_without_digit;
for my $checked (map {split /-/, $_} @account) {
    if ($checked =~ /^\d/) {
        push @account_starting_with_digit, $checked;
    }
    else {
        push @account_starting_without_digit, $checked;
    }
}
print "*" . (join " ", @account_starting_without_digit) . "*<br>\n";
print "-" . (join " ", @account_starting_with_digit) . "-<br>\n";
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• Try to split a string, not an array
• Your source data is only partly separated with "-"

my $account = "34765-22333-333489-99867-22340-23456-3229-XLM8876-AMP77
+65-WQP22349";
my @chk_acc = split("-",$account);
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HTH, Rata (wondering about the useless chomp() ... not the first time today ...)

    foreach my $checked (@chk_acc) 
     {
       chomp();
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chomp() is short for chomp( $_ ) but you don't assign any value to $_ so the use of chomp there is superfluous.

       if($checked=~/^(\w{3})(\d{4,7})/ig)
        {
          # it should print the accounts starting with letters here
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The \w character class matches all upper case letters and all lower case letters and all digits and the '_' character so the use of the /i option is superfluous and the comment is wrong because \w will also match digits and '_'.    The regular expression is anchored at the beginning of the string in $checked so it will only match once so the use of the /g is also superfluous.    You are also capturing two strings which you aren't using so the capturing parentheses are also superfluous.    So, to sum up, you probably want something like:

       if ( $checked =~ /^[[:alpha:]]{3}\d{4,7}/ )
        {
          # it should print the accounts starting with letters here
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use warnings;
use strict;

my @account = qw(34765-22333-333489-99867-22340-23456-3229 XLM8876 AMP
+7765 WQP22349);

my @chk_acc = map {split('-')} @account;

foreach my $checked (@chk_acc) 
{
    # chomp();
    if ($checked =~ /^(\w{3})(\d{4,7})/ig)
    {
        # it should print the accounts starting with letters here
        print "*$checked*<br>";
    }
    else {
        # else the rest of the accounts not starting with any letters
        print"-$checked-<br>";
    }
               
}
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if ($checked =~ /^\w{3}\d{4,7}/)
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