C# return value invoke variables in loop

Question

Here is the text file

country1: 93#country2: 355#country3: 213#country4: 376#country5: 244#country6: 54#country7: 374#

For this ASP.NET web services,when i declare string temp ouside "for" loops, Error "Use of unassigned local variable 'temp'"

  [webMethod]
    public string[] getContryCode ()

        {
            string temp;

            string[] data = File.ReadAllLines(@"countryCode.txt");

            string[] country = data[0].Split('#');

            for (int i = 0; i < country.Length; i++ )
            {
                temp = country[i];

            }
                //const string f = "countryCode.txt";

            return temp.Split(':');


        }

If i declare string temp inside a loop,i can't return a value of "temp.Split(':')". Need find a way to solve it

originl file format: #country1:code1#country2:code2# array list 'country': [0] country1 code1 country2 code2 - i can get this work b split temp.split(':') : should get things like this [0]country1 [1] code1 [2] country2 [3] code2

What is the value of `temp` when you try to `.Split` it if `country.Length` is `0`? — Kirk Woll, Aug 30 '13 at 14:27
@Kirk Woll that text file is a country code list, i want get a array from original format #country1:code1#country2:code2# to [0]country1 [1] code1 [2] country 2 [3] code2 — atom2ueki, Aug 30 '13 at 14:31
@atom2ueki: Do you have any hashtags accidentally beside each other? As in "##"? — Chris Sinclair, Aug 30 '13 at 14:35
You shouldn't read all of the lines if you only want the first one. That's a lot of wasted effort. Use `File.ReadLines("").First()` to get the first line without processing more than you need to. — Servy, Aug 30 '13 at 14:35

JDB · Accepted Answer · 2013-08-30T14:48:41.937

Your for loop is not guaranteed to iterate once, so you are getting a compiler error that temp may not have a value when you attempt to use it.

Try:

string temp = "";

Even better, though, would be to add proper testing to ensure that all of your inputs are as expected:

if ( !System.IO.File.Exists( @"countryCode.txt" ) )
    throw new ApplicationException( "countryCode.txt is missing" );

string[] data = File.ReadAllLines(@"countryCode.txt");

if ( data.Length == 0 )
    throw new ApplicationException( "countryCode.txt contains no data" );

if ( data[0].Length == 0 )
    throw new ApplicationException( "malformed data in countryCode.txt" );

string[] country = data[0].Split('#');

string temp = "";
for (int i = 0; i < country.Length; i++ )
{
    temp = country[i];
}

return temp.Split(':');

I am not really sure what you are trying to accomplish with the for-loop, though, since you are only going to be returning the last item in the country array, which would be the same as: return country[country.Length - 1];

EDIT:

You may want to remove empty entries in your country array. You can just use the RemoveEmptyEntries option:

string[] country = data[0].Split('#', StringSplitOptions.RemoveEmptyEntries);

/* Using the RemoveEmptyEntries option can cause the function to
   return a 0-length array, so need to check for that afterall: */
if ( country.Length == 0 )
    throw new ApplicationException( "malformed data in countryCode.txt" );

@Servy - my bad. I was confusing this with VB, which generates a warning (but which many people configure to act as an error) — JDB, Aug 30 '13 at 14:38
Regarding your comment on the for loop, I'll bet this is why it's returning an empty string every time. I bet the text file line _ends_ with a "#" character, thus it has a "country" that's just an empty string. — Chris Sinclair, Aug 30 '13 at 14:38
The `for` loop is still very silly. It overwrites the same variable on each iteration and the end result is to get only the last entry in the array `country`. — Jeppe Stig Nielsen, Aug 30 '13 at 14:42
@ChrisSinclair He edited an example line into the question. You are indeed correct. — Servy, Aug 30 '13 at 14:43

C# return value invoke variables in loop

1 Answers1