Converting a std::wstring to int

15
votes

I presume this to be very simple but I cannot get it to work.

I am simply trying to convert a std::wstring to an int.

I have tried two methods so far.

The first is to use the "C" method with "atoi" like so:

int ConvertedInteger = atoi(OrigWString.c_str());

However, VC++ 2013 tells me:

Error, argument of type "const wchar_t *" is incompatable with parameter of type "const char_t *"

So my second method was to use this, per Google search:

std::wistringstream win(L"10");
            int ConvertedInteger;
            if (win >> ConvertedInteger && win.eof())
            {
                // The eof ensures all stream was processed and
                // prevents acccepting "10abc" as valid ints.
            }

However VC++ 2013 tells me this:

"Error: incomplete type not allowed."

What am I doing wrong here?

Is there a better way to convert a std::wstring to int and back?

Thank you for your time.

2
c++c++11
Did you #include <sstream>? Your code with the stringstream should work. - Praetorian
Please try to convert string using int ConvertedInteger = _wtoi(OrigWString);... - A B
You could always construct a std::string from the string and use std::stoi on that. You might incur a memory allocation if the number is big enough, but I doubt it's any worse than using stringstreams. - Stuart Olsen
also I think #include <istream> is required for wistringstream - M.M

2 Answers

42
votes

No need to revert to C api (atoi), or non portable API (_wtoi), or complex solution (wstringstream) because there are already simple, standard APIs to do this kind of conversion : std::stoi and std::to_wstring.

#include <string>

std::wstring ws = L"456";
int i = std::stoi(ws); // convert to int
std::wstring ws2 = std::to_wstring(i); // and back to wstring
-1
votes

you can use available API from wstring.h.

to convert WString to int try int ConvertedInteger = _wtoi(OrigWString);.

for reference use msdn.microsoft.com/en-us/library/aa273408(v=vs.60).aspx.