How to check if a position in a string is empty in c#

Question

Hi,

I have strings with space seperated values and I would like to pick up from a certain index to another and save it in a variable. The strings are as follows:

  John Doe        Villa Grazia           323334I

I managed to store the id card (3rd column) by using:

if (line.length > 39)
{
   idCard = line.Substring(39, 46);
}

However, if I store the name and address (1st and 2nd columns) with Substring there will be empty spaces since they are not of the same length (unlike the id cards). How can I store these 2 values and removing the unneccasry spaces BUT allowing the spaces between name and surname?

Many thanks in advance.

Regards, Chris

Answer 1

var values = line.Split(' ');
string name = values[0] + " " + values[1];
string idCard = values[4];

It will be impossible to do without database lookups on names if there aren't spaces for sure in the previous columns.

Answer 2

How can you even get the ID like that, when everything in front of it is of variable length? If that was used for my name, "David Hedlund 323334I", the ID would start at pos 14, not 39.

Try this more dynamic approach:

var name = str.Substring(0, str.LastIndexOf(" "));
var id = str.Substring(str.LastIndexOf(" ")+1);

Answer 3

Try this:

string line    = "  John Doe        Villa Grazia           323334I";
string name    = line.Substring(02, 16).Trim();
string address = line.Substring(18, 23).Trim();
string id      = line.Substring(41, 07).Trim();

Answer 4

Looks like your parsing strategy will cause you a lot of trouble. You shouldn't count on the string's size in order to parse it.

Why not save the data in CSV format (John Doe, Villa Grazia, 323334I)? that way, you can assume that each "column" will be separated by a comma which will make your parsing efforts easier.

Answer 5

Possible "DOH!" question but are you sure they are spaces and not Tabs? Looks like it "could" be a tab seperated file?

Also for browie points you should use String.Empty instead of ' ' for comparisons, its more localisation and memory friendly apparently.

Answer 6

Are these actually space separated or are they really fix width columns?

By that I mean do the "columns" start at the same index into the string in each case - from the way you're describing the data is sounds like the later i.e. the ID column is always column 39 for 7 characters.

In which case you need to a) pull the columns using the appropriate substring calls as you're already doing and then, use "string ".Trim() to cut off the spaces.

If the rows, are, as it seems fixed with then you don't want to use Split at all.

Answer 7

The first approach would be - as already mentioned - a CSV-like structure with a defined token as the field separator.

The second one would be fixed field lengths so you know the first column goes from char 1 to char 20, the second column from char 21 to char 30, and so on. There is nothing bad about this concept besides that the human readability may be poor if the columns are filled up to their maximum so no spaces remain between them.

You could write a helper function or class which knows about the field lengths and provides an index-based, fault-tolerant access to the particular column. This function would extract the particular string parts and remove the leading and trailing spaces but leave the spaces in between as they are.

Answer 8

If your values have fixed width, best not split it but use the right indexes in your array.

const string input = "John Doe        Villa Grazia           323334I";
var name = input.Substring(0, 15).TrimEnd();
var place = input.Substring(16, 38).TrimEnd();
var cardId = input.Substring(39).TrimEnd();

Assuming your values cannot contain two sequential spaces in them we can maybe use " " (double space" as a separator?
The following code will split your string based on the double space

const string input = "John Doe        Villa Grazia           323334I";
var entries = input.Split(new[]{"  "}, StringSplitOptions.RemoveEmptyEntries)
                .Select(s=>s.Trim()).ToArray();
string name = entries[0];
string place = entries[1];
string idCard = entries[2];