How do I convert a single char/wchar to a single-character string/wstring in d? I can't find anything online that doesn't talk about char* or wchar*.
2 Answers
There's a few different options. One is to get a pointer by just taking the address of it. You generally shouldn't use this but you should be aware it is possible.
char a = 'a';
char[] b = (&a)[0 .. 1]; // &a gets a pointer, [0..1] slices the single element
string c = b.idup; // copy it into a new string
If you used a wchar you could get a wstring out of it this way. Then std.conv.to can convert between string and wstring.
Speaking of std.conv.to, that's the next option and is actually the easiest:
import std.conv;
char a = 'a'; // or wchar
string b = to!string(a); // or to!wstring
In the real world I'd probably suggest you use this for maximum convenience and simplicity, but you lose a bit of efficiency in some cases.
Thus, the third option I'll present is std.utf.encode.
import std.utf;
char[4] buffer;
auto len = encode(buffer, a); // put the char in the buffer
writeln(buffer[0 .. len]); // slice the buffer. idup it if you want string specifically
This works for any input: char, wchar, or dchar, and will encode multi-byte code points into the string as well. To get a wstring, use wchar[2] for the buffer isntead. This is a good balance of correctness and efficiency, just at the trade of being a little less convenient.
As strings are just immutable(char)[], you can construct them like any other array with chars:
char a = 'a';
string s = [a];
Related