CODEWITHSUNDEEP
c++
Sebastian
Sebastian

Reputation: 1960

Difference between System::Convert::ToString() and std::to_string()?

I'm a complete noob in Visual C++ programming, so I don't know if this makes sense or not.

Well, I'm trying to change a label text to display in a form, so if I do this:

int value_a = 1;
int value_b = 2;
System::String^ j;
j = System::Convert::ToString(value_a) + ", " + System::Convert::ToString(value_b);
label1 -> Text = j;

It works perfectly, but when I tried doing this:

int value_a = 1;
int value_b = 2;
System::String^ j;
j = std::to_string(valor1) + ", " + std::to_string(valor2);
label1-> Text = j;

I get plenty of errors... What's the difference between using 

string j;

or

System::String^ j;

and between the functions

System::Convert::ToString();

and

std::to_string();

????

Upvotes: 3

Views: 6078

Answers (2)

IdeaHat
IdeaHat

Reputation: 7881

The source of your confusion is probably that you are using C++/CLI, so you have access to many different string types. C++/CLI was developed to give you access to both worlds:

  1. Unmanaged: this is basically native, standard C++ code. While C++/CLI in no way conforms to the C++ standard, it does allow you to mix C++ code in: you can use most C++ libraries (through the "it just works paradigm"). This code is called "unmanaged" because you have to do your own memory management.
  2. Managed: This is the .NET side of things. Using .net classes, you have access to the useful libraries that microsoft puts out, as well as can work with the garbage collector.

System::String is the managed, .NET string type. This is the type of string that all .NET languages use (C#, VBA, ect). This is a class that will only be able to use with C++/CLI & .NET. Use this type if you are writing pure Windows code, or if want to write a .NET library. In these languages, the "to string" function is actually a member of all classes, and the cast is often implicit. You can use 

j = valor1+","+valor2;

If you want to get explicit, look into the Int::ToString function:

System::String^ j= Int32(1).ToString();

std::string is the unmanaged, stl string. This is the standard C++ class, and is available to both C++ and C++/CLI. You will have to marshal this class if you want to use it with other .NET classes. Use this class if you are trying to stay completely in the unmanaged code.

If you are trying to learn C++, I'd suggest turning off C++/CLI for now, and sticking with the standard library string.

Upvotes: 0

Tony The Lion
Tony The Lion

Reputation: 63200

System::String^ j; is a C++/CLI String which is Microsoft's implementation of C++ on top of the .NET framework, so you can communicate from it with .NET languages (C#, VB.NET) and still use C++. The ^ is a garbage collected pointer used by C++/CLI. This means that you do not have to care about cleaning up after yourself when having used gcnew

std::string is the C++ Standard Library's version of a string. It's native C++ as some may call it.

In C++ each time you use new with a pointer, yuck, you must not forget to call delete.

System::Convert::ToString is also C++/CLI from Microsoft.

std::to_string would be the C++11 equivalent of that.

The implementations are quite different, so you cannot expect to get the same results with these different types.

Upvotes: 3

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