how to extract a value with a specific character out of an character array

a great example to describe this would be for emails. Say we have an input of:

emails = 'someone, random@gmail, other'

how would one know to select the one with the @gmail and then add the .com to the end after?

If there are multiple emails in the array, only display the first one.

Answer 1

[DGM]

I'm not sure which extra emails should be rejected. I'm going to assume that all other emails get rejected

emails = {'someone, random@gmail, backupaccount@yahoo, other';
	'someone else, random2@hotmail, other'};

mailhost = regexp(emails,'@[^,]*','match');
mailhost1all = [mailhost{1}{1} '.com']

mailhost1all = '@gmail.com'

If instead there might be more than one email per entry in the emails array, and you only want the first email per entry in the array:

mailhost1each = cell(numel(emails),1);
for acct = 1:numel(emails)
    mailhost1each{acct} = [mailhost{acct}{1} '.com'];
end
mailhost1each

mailhost1each = 2×1 cell array
    {'@gmail.com'  }
    {'@hotmail.com'}

[Elena]

it would need to include the username of the email as well. It can work for both @gmail and @yahoo, but it it's @earthlink it would need to end with .net instead of .com

[Rik]

mailhost1each=strrep(mailhost1each,'@earthlink.com','@earthlink.net');

[DGM]

Maybe something like this?

emails = {'someone, random@gmail, backupaccount@yahoo, other';
    'someone else, random2@earthlink, other'};

% match the whole email address
mailaccounts = regexp(emails,'[^,\s]*?@[^,]*','match');

% these hosts should be .net
hasnettld = {'earthlink','comcast','airmail','charter'};
hasnettld = cellfun(@(x) ['@' x],hasnettld,'uniform',false); 

firstmailaccounts = cell(numel(emails),1);
for acct = 1:numel(emails)
    thisacct = mailaccounts{acct}{1};
    if contains(thisacct,hasnettld)
        firstmailaccounts{acct} = [thisacct '.net'];
    else
        firstmailaccounts{acct} = [thisacct '.com'];
    end
end

firstmailaccounts

firstmailaccounts = 2×1 cell array
    {'[e-mail]'     }
    {'[e-mail]'}

I'm sure this can be simplified, but I'm still not really sure what you want matched.