Not all code paths return a value in C#

Question

1.44/5 (3 votes)

See more:

Hi Developers,

I am having simple function as mentioned below:

C#

public static string GetCodeName(int machineId)
        {
            var dc = new CEWBDataContext();
            var codename = ModelTypes(machineId, dc).Select(x => x.CodeName).ToList();
            if (codename.Any())
                return codename.FirstOrDefault();
        }

I am facing the signature error saying
"

Not all code paths return a value

"

what is wrong in the above code.

What I have tried:

I have tried below and its works fine. But what is the problem with the above code

if (codename.Count > 0)
               return codename.ToList()[0];
           else
               return null;

Posted 11-Nov-19 18:02pm

D-Kishore

Updated 15-Nov-20 7:43am

v2

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

David_Wimbley · Answer 1 · 2019-11-11T18:24:00

Solution 1

Your problem is exactly as it states and what you've tried is your exact solution.

You've got a condition in your code that says if(codename.Any()) { return codename.FirstOrDefault(); } but you have no else condition.

Your method has to return a string regardless of what fashion it is in. If there is no codename you should return string.Empty or null.

Ex: if(codename.Any()) { return codename.FirstOrDefault(); } else { return string.Empty; }

Then in the portion of your code that consumes this method, you need to implement some sort of error handling to say

var codename = MyClass.GetCodeName(1); if(string.IsNullOrEmpty(codename) { //do some sort of error here, throw an exception, do something about the error...etc }

You must have an else condition or a ternary operator in your GetCodeName method. There is no way around it.

Posted 11-Nov-19 18:24pm

David_Wimbley

Updated 11-Nov-19 18:26pm

v2

Comments

D-Kishore 12-Nov-19 1:12am

Thanks you, But the we are using that FirstOrdefault(), I thought that this will take care if the value had null also.

David_Wimbley 12-Nov-19 2:46am

First or default has nothing to do with how a method works or available return values.

A method must have a return value regardless of its value. Your IF statement is preventing any values being returned if codename.Any() is false. If its true, you have a return value.

Based on your comment it seems you need to get rid of your if statement and just return FirstOrDefault as the .Any() check is redundant.

Ex: Change
if (codename.Any())
return codename.FirstOrDefault();

To just

return codename.FirstOrDefault();

That should accomplish what you seem to be indicating you need. Regardless of any contents within the codename List, it will return first or default (in this case null if the list is empty).

D-Kishore 12-Nov-19 3:50am

Thanks David, for clearing my clarifications.

Richard Deeming 12-Nov-19 11:08am

NB: Since you're using FirstOrDefault, you don't need that if block at all. Neither do you need the ToList call.

var dc = new CEWBDataContext();
return ModelTypes(machineId, dc).Select(x => x.CodeName).FirstOrDefault();