String array in constructor

[mattias.k.nyberg]

So Im trying to learn to program with C#. And I have this question
about why the string array won't work in the first class but it does in
the second. To me it looks like they do the exact same thing.

class Test
{
string[] words;
public Test() {
words = { "", "", "" }; // This doesn't work
}
}

class Test2
{
string[] words;
public Test2() {
words = new string[3]; // This works
}
}

 

[Keunho Yoo]

kk

 

[Keunho Yoo]

test sorry

 

[Mel]

you must set the length of a static array before using it

sring[] words = new String[3] {"","",""};

or string[] words = new String[3];
words[0] = "";
words[1] = "";
words[2] = "";

 

[Keunho Yoo]

d

 

[mattias.k.nyberg]

Hmmm, why does this work then?

class Test
{
string[] words = { "", "", "" };
}


But not this:

class Test
{
string[] words;
public Test() {
words = { "", "", "" };
}
}

you must set the length of a static array before using it

sring[] words = new String[3] {"","",""};

or string[] words = new String[3];
words[0] = "";
words[1] = "";
words[2] = "";

So Im trying to learn to program with C#. And I have this question
about why the string array won't work in the first class but it does in
the second. To me it looks like they do the exact same thing.

class Test
{
string[] words;
public Test() {
words = { "", "", "" }; // This doesn't work
}
}

class Test2
{
string[] words;
public Test2() {
words = new string[3]; // This works
}
}

 

[Brian Gideon]

In the first class the line should be the following to compile
correctly.

words = new string[] { "", "", "" };

The second class is not doing the same thing. All it is doing is
creating an array big enough to hold 3 strings, but doesn't actually
initialize the strings. Contrast that with what I have above which
does initialize the strings.

It's been awhile since I've read the specification, but I believe C#
3.0 will accept the syntax in your first class.

Brian

 

[Brian Gideon]

It's been awhile since I've read the specification, but I believe C#
3.0 will accept the syntax in your first class.

I just did a cursory check of the specification. I found nothing
indicating this was true.

 

[mattias.k.nyberg]

Ah I see now.

This only works if you keep it on the same line.
string[] words = { "", "", "" };

It doesn't if you split it up.
string[] words;
words = { "", "", "" }; // Error

Then I need to use:
string[] words;
words = new string[] { "", "", "" };


Thanks for the help

In the first class the line should be the following to compile
correctly.

words = new string[] { "", "", "" };

The second class is not doing the same thing. All it is doing is
creating an array big enough to hold 3 strings, but doesn't actually
initialize the strings. Contrast that with what I have above which
does initialize the strings.

It's been awhile since I've read the specification, but I believe C#
3.0 will accept the syntax in your first class.

Brian

So Im trying to learn to program with C#. And I have this question
about why the string array won't work in the first class but it does in
the second. To me it looks like they do the exact same thing.

class Test
{
string[] words;
public Test() {
words = { "", "", "" }; // This doesn't work
}
}

class Test2
{
string[] words;
public Test2() {
words = new string[3]; // This works
}
}

 

[Chris Dunaway]

Hmmm, why does this work then?

More than likely the compiler uses that as shorthand for the full
declaration. I'm not certain of this though.

 

[Bill Butler]

Hmmm, why does this work then?

class Test
{
string[] words = { "", "", "" };
}

You can only initialize arrays this way at the time they are declared
string[] words = { "", "", "" };
is shorthand for
string[] words = new string[]{"","",""};
but only in the declaration

I don't know the reason why it is limited to the declaration. On the
surface it seems like a reasonable thing to want to do, but perhaps the
devil is in the details.

Hope this helps
Bill

But not this:

class Test
{
string[] words;
public Test() {
words = { "", "", "" };
}
}