String vs string

Andrew

15y2.3kVisual Basic .NET

Hey buddies!

Is there any difference between String and string. If any, please post it here.... :)

10 Replies

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Sam Hobbs15y ago
Accepted answer
The capitalized version ("String") is a class in the .Net System namespace. The uncapitalized one ("string") is part of the C# language.

Try this. Create a new Console applicaiton. Remove all the "Using" statements at the top. Then put the following in the Main:
string s1 = "Hello";
String s2 = "Hello";

You will get an error for s2 but not s1, because s1 is an alias for "System.String". That means that you do not need a Using for it but you do need either a Using for "String" or without a Using you need to specify System.String. Note that "string" is an alias for System.String and since you are not likely to ever write a program without a Using for System, Vulpes's and John's replies are correct.
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Manikavelu Velayutham15y ago
Thats an awesome example :)
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Vulpes15y ago
Incidentally, one good reason for preferring C#'s built in keywords is that they are unambiguous - 'string' is always the same as System.String.

This is important because there is nothing to stop a library writer from creating a class called 'String' in a different namespace, though it would be bad practice to do so. When you add a reference to this library and import the namespace, you are then faced with potential ambiguity problems.

For example, consider this code (for simplicity I've put all the code in one program):

using System;
using Vulpes;

namespace Vulpes
{
public class String
{
}
}

static class Program
{
static void Main()
{
string s = "clarity";
String t = "confusion"; // compiler error - ambiguous reference

}
}

If you don't use the C# keyword, the only way to resolve the ambiguity is to change the offending line to:

System.String t = "clarity again"; // now using fully-qualified type name

Also it's not possible to create a class called 'string'. The C# compiler won't let you as it's a keyword.

However, you can create a class called @string. This is because keywords can be used as ordinary identifiers if they are preceded by '@'.
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Manikavelu Velayutham15y ago
Thanks for clearing my doubt Vulpes
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Vulpes15y ago
C# has a number of keywords which are just aliases for types in the System namespace. Here are a few examples:

string -> String
int -> Int32
long -> Int64
double -> Double
float -> Single

This was done so that C# would seem more familiar to C/C++/Java programmers and to give the C# language some character of its own compared to other .NET languages.

However, whether you use the C# keywords or the .NET Framework types is a matter of taste and some developers prefer to use the latter.
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Manikavelu Velayutham15y ago
If .NET itself has the System.String, then what is the purpose of including string in C# language.

Surely there will be some reason behind it, right ?

Is it like Common Language Specification ?
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Mahesh Chand15y ago
All questions are correct.

In theory and from language perspective, string is a data type like int or char in C# language.

String is a class that represents the string data type and is a part of .NET Framework.
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Vilas Gite15y ago
Hi Andew..

Refer for more details :

http://msdn.microsoft.com/en-us/library/362314fe(v=vs.71).aspx

Same Thread : http://stackoverflow.com/questions/7074/in-c-what-is-the-difference-between-string-and-string

string Vs String : http://en.csharp-online.net/CSharp_String_Theory—string_versus_String
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Guest User15y ago
There is no difference (functionally speaking).
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Vulpes15y ago
As long as you have this using directive in your program, there isn't any difference:

using System;

This is because the C# keyword 'string' is just an alias for System.String.
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