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

Question

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();

????

In both cases, one is C++/CLI and one is standard C++. Differences are to be expected. — Qaz
– Qaz, Commented Mar 20, 2013 at 20:21
A look at the documentation would answer that question – the types mismatch! — Konrad Rudolph
– Konrad Rudolph, Commented Mar 20, 2013 at 20:26

Tony The Lion · Accepted Answer · 2013-03-20 20:40:16Z

3

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.

answered Mar 20, 2013 at 20:40

Tony The Lion

63.6k71 gold badges252 silver badges424 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

IdeaHat · Accepted Answer · 2013-03-20 20:41:04Z

0

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:

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.
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.

answered Mar 20, 2013 at 20:41

IdeaHat

7,9311 gold badge28 silver badges57 bronze badges

2 Comments

Sebastian Over a year ago

I see, but the text attribute of Visual Studio's form labels seem to only accept the Managed string... Is there a way to go from one to the other?

IdeaHat Over a year ago

I have this handy look up table bookmarked: [msdn.microsoft.com/en-us/library/vstudio/bb384865.aspx]

Collectives™ on Stack Overflow

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

2 Answers 2

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related