CODEWITHSUNDEEP
stringwindowsvisual-c++windows-10-universalc++-cx
Zeke Medley
Zeke Medley

Reputation: 371

How to access individual character in Platform::String?

How can I access an individual character in Platform::String^?

I am using this variable type because it appears to be the only way to write a string to a TextBlock on a Universal Windows App.

I have tried the following methods to get individual characters to no avail:

String ^ str = "string";
std::string::iterator it = str->begin(); //Error: platform string has no member "begin"
std::string::iterator it = str.begin(); //Error: expression must have a class type
str[0] = 't' /*Error: expression must have a pointer-to-object or handle-to-C++/CX 
mapping-array type*/

I am putting the String^ in a text block named "textBlock" as follows: textBlock->Text = str;

I am open to approaches other than modifying the Platform::String. My only requirement is that the string ends in a form that can be put into a TextBox

Upvotes: 0

Views: 666

Answers (2)

user3164339
user3164339

Reputation: 166

An addition to the already supplied answer: you are also able to change a Platform::String^ into a std::wstring so you can modify it, then you can always change it back to Platform::String^

Platform::String^ str = "string";
wstring orig (str->Data());
orig[0] = L't';
str = ref new Platform::String(orig.c_str());

Upvotes: 0

IInspectable
IInspectable

Reputation: 51395

Platform::String represents a sequential collection of Unicode characters that is used to represent text. The controlled sequence is immutable: Once constructed, the contents of a Platform::String can no longer be modified.

If you need a modifiable string, the canonical solution is to use another string class, and convert to/from Platform::String when calling the Windows Runtime, or receiving string data. This is explained under Strings (C++/CX):

The Platform::String Class provides methods for several common string operations, but it's not designed to be a full-featured string class. In your C++ module, use standard C++ string types such as wstring for any significant text processing, and then convert the final result to Platform::String^ before you pass it to or from a public interface.

You could rewrite your code sample as follows:

// Use a standard C++ string as long as you need to modify it
std::wstring s = L"string";
s[0] = L't';    // Replace first character

// Convert to Platform::String^ when required
Platform::String^ ps = ref new Platform::String(s.c_str(), s.length());

Upvotes: 2

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