We Keep Coding

How many string object are created when using string concatenation in C#

I'm a beginner in C#, just have some question on string concatenation.
string str = "My name is";
str += "John"
Q1-Does C#(.NET) have the same concept string pool in Java?
Q2- how many string object are created?

Q1-Does C#(.NET) have the same concept string pool in Java?
T̶h̶e̶ ̶a̶n̶s̶w̶e̶r̶ ̶i̶s̶ ̶n̶o̶,̶ ̶u̶s̶i̶n̶g̶ ̶s̶t̶r̶i̶n̶g̶s̶ ̶i̶n̶ ̶C̶#̶ ̶i̶s̶ ̶n̶o̶t̶ ̶l̶i̶k̶e̶ ̶t̶h̶e̶ ̶s̶t̶r̶i̶n̶g̶ ̶p̶o̶o̶l̶ ̶i̶n̶ ̶j̶a̶v̶a̶, each string is its own reference;
Correction : I had to research this for Java... It is conceptually the same thing, i was mistaken about the details of Javas string pool
C# commonly calls it string interning
You can read more about it here at Fabulous Adventures In Coding : Eric Lippert's Erstwhile Blog
String interning and String.Empty
If you have two identical string literals in one compilation unit then
the code we generate ensures that only one string object is created by
the CLR for all instances of that literal within the assembly. This
optimization is called "string interning".
String interning is a CLI feature that reuses a string instance in certain situations :
string literals, created via the ldstr IL command
When invoked explicitly using string.Intern
Q2- how many string object are created?
Because strings in C# are immutable, you get 3 string allocations out of your 2 statements
// 1st string
string str = "My name is";
// 2nd string
// "John"
// 3rd string, which is the concatenation of the first 2
str += "John"

Yes, there is such a thing.
The common language runtime conserves string storage by maintaining a table, called the intern pool, that contains a single reference to each unique literal string declared or created programmatically in your program. Consequently, an instance of a literal string with a particular value only exists once in the system.
source
In your case, I believe there will be three allocations.

Naming conflict with keyword object [duplicate]

This question already has answers here:
Use the long reserved word as a variable name in C#
(5 answers)
Closed 6 years ago.
So I have this simple problem that I'm struggling with. Consider this code:
namespace Foo
{
public class Bar
{
public void Test(string object)
{
}
}
}
This function throws a syntax error because object is a keyword in C#. Is there a way to solve that? In my real code I have a framework that uses function's signature to create an API and I should really use object name as parameter.

Use # before parameter name #object to use keyword as identifier
public void Test(string #object)
From C# Language Specification 2.4.2 Identifiers:
The rules for identifiers given in this section correspond exactly to those recommended by the Unicode Standard Annex
31, except that underscore is allowed as an initial character (as is
traditional in the C programming language), Unicode escape sequences
are permitted in identifiers, and the “#” character is allowed as a
prefix to enable keywords to be used as identifiers.

The # symbol allows you to use reserved word. For example:
int #class = 15;
The above works, when the below wouldn't:
int class = 15;

Difference between string.Empty and String.Empty in C# [duplicate]

This question already has answers here:
What is the difference between String and string in C#?
(66 answers)
Closed 9 years ago.
What is the difference between string.Empty and String.Empty in C#? Also note the colors are different. They both reference or are of type class System.String

It is the same. string is an alias of class System.String.
some common aliases:
object ==> System.Object
string ==> System.String
bool ==> System.Boolean
int ==> System.Int32
float ==> System.Single
double ==> System.Double
decimal ==> System.Decimal
char ==> System.Char

String.Empty and string.Empty are same. String is the BCL class name. string is the C#...shortcut if you will. Same as with Int32 and int.

Both are SAME except that string is treated as a keyword with Blue color (default) and System.String is a Class with Green Color (default) in the VS editor.
Underlying implementation are all the same. In other words points to the same.

In C#, the string keyword is an alias for String. Therefore, String and string are equivalent, and you can use whichever naming convention you prefer. The String class provides many methods for safely creating, manipulating, and comparing strings. In addition, the C# language overloads some operators to simplify common string operations

What is the difference between char and Char? [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
What is the difference between String and string
When I run:
char c1 = 'a';
Console.WriteLine(c1);
and when I run:
Char c2 = 'a';
Console.WriteLine(c2);
I get exactly the same result, a.
I wanted to know what is the difference between the two forms, and why are there two forms?

The result is exactly the same. Both represent the same type, so the resulting executables are completely identical.
The char keyword is an alias in the C# language for the type System.Char in the framework.
You can always use the char keyword. To use Char you need a using System; at the top of the file to include the System namespace (or use System.Char to specify the namespace).
In most situations you can use either a keyword or the framework type, but not everywhere. For example as backing type in an enum, you can only use the keyword:
enum Test : int { } // works
enum Test : Int32 {} // doesn't work
(I use int in the example, as You can't use a char as backing type for an enum.)
Related: Difference between byte vs Byte data types in C#

As far as I know, C# char type keyword is simply an alias for System.Char, so they refer to the same type.

The keyword char is an alias of the System.Char type in C#.

C# equivalent to toSource() of javascript [duplicate]

This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Can I convert a C# string value to an escaped string literal
How I can show the contents of a string in 'pure mode',including \r,\n,\t etc..
equivalent to .toSource() method of javascript
For example:
JavaScript:
var str = "foo\nbaa\ttest";
console.log(str.toSource());
Output:
(new String("foo\nbaa\ttest"))
it is possible do this in C#?
Thanks in advance!

See the answer to Can I convert a C# string value to an escaped string literal . He wrote this extension method that does exactly what you're wanting:
static string ToLiteral(string input)
{
var writer = new StringWriter();
CSharpCodeProvider provider = new CSharpCodeProvider();
provider.GenerateCodeFromExpression(new CodePrimitiveExpression(input), writer, null);
return writer.GetStringBuilder().ToString();
}

Regex.Escape("foo\nbaa\ttest")

Looking at the general problem - reconstructing some source code - there is no language option on C# that would let you do it automagically.
However (this is theory on my part) you should be able to use expressions to get to the IL equivalent (using the Reflection.Emit or Mono.Cecil libraries perhaps). You could I suspect then use the libraries from the ILSpy project to reconstruct the C#.