Main method compiles only when it's empty

Question

I have created the following program:

namespace MyNamespace
{
    public enum MyEnum { Jan = 1, Feb = 2, Mar = 3, Apr = 4, May = 5, Jun = 6, Jul = 7, Aug = 8, Sep = 9, Okt = 10, Nov = 11, Dec = 12 }

    class Program
    {
        static void Main(string[] args)
        {
            private static string sourcePath = @"T:\his\is\my\source";
            private static string destinationPath = @"T:\his\is\my\destination";
        }
    }
}

That's all I have so far. The problem is that it doesn't compile like this. I get the following exception:

} expected

It only works when I leave the Main method body empty. When I use Ctrl + KD to format the code, it is formatted like this:

namespace MyNamespace
{
    public enum MyEnum { SomeField = 1, SomeOtherField = 2, ... }

    class Program
    {
        static void Main(string[] args)
        {
            private static string sourcePath = @"T:\his\is\my\source";
        private static string destinationPath = @"T:\his\is\my\destination";
    }
}
}

This totally doesn't make any sense. I can't even access the parameter args:

The name 'args' does not exist in the current context

I really don't know why my project is behaving like this. Did anyone else encounter the same problem? What should I do?

Could it be this line? `public enum MyEnum { SomeField = 1, SomeOtherField = 2, ... }`. Do you actually have it like that? Get rid of the ellipsis and put actual values. — rory.ap, Jan 12 '17 at 14:23
No, even when I remove the enum, I'm getting the same exception. — diiN__________, Jan 12 '17 at 14:24

Dmitry · Accepted Answer · 2017-01-12T14:32:15.357

10

You cannot declare the class fields inside a method.
Move the following lines out of it:

private static string sourcePath = @"T:\his\is\my\source";
private static string destinationPath = @"T:\his\is\my\destination";

Or if you want these variables to be local for the method, declare them as:

string sourcePath = @"T:\his\is\my\source";
string destinationPath = @"T:\his\is\my\destination";

edited Jan 12 '17 at 14:32

answered Jan 12 '17 at 14:25

Dmitry

13,797
6
32
48

And it will still fail... – leppie Jan 12 '17 at 14:27
Thank you, it works now. – diiN__________ Jan 12 '17 at 14:27
2

`@"T:\h..."` add `@`, please – Dmitry Bychenko Jan 12 '17 at 14:28
Also make the strings `const`. – Bauss Jan 12 '17 at 14:28
3

@Bauss: these strings are not necessary `constant`s – Dmitry Bychenko Jan 12 '17 at 14:29
2

Why would changing to const, solve the problem?? What's the logic in that? – Renato Afonso Jan 12 '17 at 14:30
@Renato Afonso: `private static string sourcePath...` is attempt to declare a *field* within a *method* which is syntax error (*field* can be declared within `class`/`struct` only); `const string sourcePath...` is just a *constant* (compare with `string sourcePath...` whcih is just a *variable*) which is perfectly legal. – Dmitry Bychenko Jan 12 '17 at 14:36
Note that as @DmitryBychenko comments this is not the only problem with the above code that will cause it to fail to compile, see my answer for more details – TheLethalCoder Jan 12 '17 at 14:43

score 2 · Answer 2 · edited May 23 '17 at 11:54

Assuming you have copied the code directly, you have three main mistakes. Firstly in your enum you have some ellipses at the end:

public enum MyEnum { SomeField = 1, SomeOtherField = 2, ... }

You need to remove them and if necessary put in more values.

Secondly you are trying to declare what look like fields inside of you Main method. You need to move them out of the method:

private static string sourcePath = "T:\his\is\my\source";
private static string destinationPath = "T:\his\is\my\destination";

static void Main(string[] args)
{

}

Or make them method level variables by removing the access level modifiers and the static modifier:

static void Main(string[] args)
{
    string sourcePath = "T:\his\is\my\source";
    string destinationPath = "T:\his\is\my\destination";
}

Finally your paths are constructed like so:

"T:\his\is\my\source"

Here you have back slashes which in C# strings are used to create escape sequences. You need to either escape them with another back slash:

"T:\\his\\is\\my\\source"

Or use the @ modifier on them so they are treated verbatim, see this question for more information.:

@"T:\his\is\my\source"

Side note: It is probably better to either pass your paths in as command line arguments, or use a config file, rather than hardcoding them into your code. For example (untested code):

static void Main(string[] args)
{
    if (args.Length < 2)
    {
        throw new ArgumentOutOfRangeException("Two arguments must be supplied!");
    }

    //Add error checking as appropriate
    //You could also format the arguments like -s:... and -d:...
    //Then the order of the arguments will not matter

    string sourcePath = args[0];
    string destinationPath = args[1];
}

I've added the ellipses only to show that there are other fields. I don't have them in my actual code. The problem was the variable declaration which Dmitry already mentioned. — diiN__________, Jan 12 '17 at 14:32
@diiN__________ Note my opening comment "Assuming you have copied the code directly" and there are 3 main mistakes with the code you posted whereas Dmitry only showed one. Next time post an [MCVE] otherwise you'll get extra info on what is wrong with your code like I posted — TheLethalCoder, Jan 12 '17 at 14:34

Main method compiles only when it's empty

2 Answers2