I decided to take a class at the local college here and I'm a little
confused about something.

int age = 5;

Console.WriteLine("You are " + age + " years old");

Previously, I had been reading Learning C# and I learned to type
Console.WriteLine('You are {0} years old",age);

The book I'm using now (required for course) is C# by dissection.

At the end of each project it supposidely "disects" the code etc but I don't
think it's doing a very good job because I feel like if I hadn't already
read 6 chapters of Learning C# I'd be pretty confused.

I didn't see it explain what those plus signs were about.

On another code example it's typed

Console.WriteLine(pennies + " pennies");

Why doesn't it have a plus sign before the variable this time?

Thanks

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And by adding, he means + returns a new string that represents the
concatenation of two strings.

--
Mike Mayer
http://www.mag37.com/csharp/
mike@mag37.com

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You are correct that Console.WriteLine takes numbers as parameters (it has
about 18 overloads if I counted correctly). Howver, that is not the reason
that the above compiles. You would be calling the Console.WriteLine(string)
since the result of adding strings to numbers is a longer string.

"We are at week" + nWeekNumber
calls an overloaded + operator that takes a string on the left side, an int
on the right side, and returns a string. Then call + with two strings
(result of first + and the string " of Test number "). Then call + of a
string and a number. The end result is one string, that is passed to
Console.Writeline

--
Mike Mayer
http://www.mag37.com/csharp/
mike@mag37.com

Robert,
As the others have stated the + is the string concatenation operator, under
the covers C# is calling String.Concat.

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under the covers becomes:
Console.WriteLine(String.Concat("You are ", age, " years old"));

Normally I prefer:
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As its easier to internationalize, you can replace the "You are {0} years
old" (the format) with a string in a different language (German for
example), because age is a placeholder, the position of age within the
format can move and the Console.WriteLine will still succeed. When
internationalizing you would read the format from a Resource file (.resx or
..resources) using a System.Resources.ResourceManager.

Hope this helps
Jay

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+ add's two strings together.

string szText = "Hello " + "there...";

while the {###} syntax, where ### are numbers from 0 to how many variables
are concerned, takes values that are non-string type, such as int, and
inserts them into your string.

Console.WriteLine ("We are at week {0} of Test number {1}", nWeekNumber,
nTestNumber );

note the following would be invalid:

Console.WriteLine ("We are at week " + nWeekNumber + " of Test number "
+ nTestNumber );

it's invalid because nWeekNumber and nTestNumber cannot be added to a
string, because they are not strings themselves.

hope that helps.
Dan.


[quoted text, click to view]
I decided to take a class at the local college here and I'm a little
confused about something.

int age = 5;

Console.WriteLine("You are " + age + " years old");

Previously, I had been reading Learning C# and I learned to type
Console.WriteLine('You are {0} years old",age);

The book I'm using now (required for course) is C# by dissection.

At the end of each project it supposidely "disects" the code etc but I don't
think it's doing a very good job because I feel like if I hadn't already
read 6 chapters of Learning C# I'd be pretty confused.

I didn't see it explain what those plus signs were about.

On another code example it's typed

Console.WriteLine(pennies + " pennies");

Why doesn't it have a plus sign before the variable this time?

Thanks

The plus sign is simply an indication that you add up different strings.

string str1 = "You are ";
string str2 = age.ToString(); // using an int in Write(Line) causes it to
be converted to a string
string str3 = " years old";

So the first sentence can now be written like
string str4 = str1 + str2 + str3;
Console.WriteLine(str4);

The second line contains only two strings that are added
string str1 = pennies;
string str2 = " pennies";
Console.WriteLine(str1 + str2);

--

This makes better sense after you explained it since I'm slightly familiar
with PHP and it uses a . instead of a +

echo "Welcome ".$currentUser."!";

so, depending where the variable is being added, before preiod goes after,
between, on both sides, and after period goes before.


Okay, so if I'm understanding you guys correctly {3} is the old way

and + is the new way?

And I probably shouldn't use {0} anymore? or does it depend...

because I thought I remember that if you type something like this
Console.WriteLine("The current road conditions are {0}", (int) icey);

and that would display icey intead of the variable assigned to icey?

I'm not possitive if I typed that correctly, I'd have to go back to my other
book to make sure.

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I meant it would display icey instead of the value assigned to icey

in C#, does it matter if there is a space between the + and the variable?
there's not space between the period in PHP.

or is that just a programmers style preference?

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Actually, this would compile just fine, because WriteLine accepts numbers
as parameters.
--

I believe that when you use the + operator in java, it returns a
StringWriter object, which allows a statement like:

String a = "h" + "e" + "l" + "l" + "o";

to execute just as quickly as if we created a StringWriter and kept
appending letters to it. I was hoping that this was the case in C#, so I
ran the following test. Now, it could be that I just don't understand
reflection well enough in c# yet, or that the + operator is somehow
optimized, so i'd really appreciate some feedback. as of now, it seems
that using the "{###}" notation is more optimized because each string is
only copied once.

public static void Main()
{
string a = "Hello ";
string b = "World!";
Console.WriteLine((a + b).GetType());
}

outputs: System.String

cheers,
ben

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