c++ integer->std::string conversion. Simple function?

Question

Problem: I have an integer; this integer needs to be converted to a stl::string type.

In the past, I've used stringstream to do a conversion, and that's just kind of cumbersome. I know the C way is to do a sprintf, but I'd much rather do a C++ method that is typesafe(er).

Is there a better way to do this?

Here is the stringstream approach I have used in the past:

std::string intToString(int i) { std::stringstream ss; std::string s; ss << i; s = ss.str(); return s; }

Of course, this could be rewritten as so:

template<class T> std::string t_to_string(T i) { std::stringstream ss; std::string s; ss << i; s = ss.str(); return s; }

However, I have the notion that this is a fairly 'heavy-weight' implementation.

Zan noted that the invocation is pretty nice, however:

std::string s = t_to_string(my_integer);

At any rate, a nicer way would be... nice.

Related:

Alternative to itoa() for converting integer to string C++?

In your example t_to_string I fail to see why a template specification is required. A template function can determine its template type from its argument types. — Zan Lynx
– Zan Lynx, Commented Jul 28, 2010 at 22:06
@Zan: Durp. That's what I get for posting code I didn't compile. — Paul Nathan
– Paul Nathan, Commented Jul 28, 2010 at 22:13
How about some of the examples from the following: codeproject.com/KB/recipes/Tokenizer.aspx They are very efficient and somewhat elegant. — Matthieu N.
– Matthieu N., Commented Nov 2, 2010 at 5:01
@Beh: That library is considerably heavier-weight than a simple t_to_string(). It actually looks like a very nice library, but I wouldn't want to import the whole thing for just doing a t_to_string(). — Paul Nathan
– Paul Nathan, Commented Nov 8, 2010 at 17:38

tanguy_k · Accepted Answer · 2012-02-27 19:50:38Z

138

Now in c++11 we have

#include <string> string s = std::to_string(123);

Link to reference: http://en.cppreference.com/w/cpp/string/basic_string/to_string

edited Feb 27, 2012 at 19:50

tanguy_k

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answered Dec 2, 2011 at 20:12

Johannes Schaub - litb

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3 Comments

Paul Nathan Over a year ago

Very spiffy. Have a link to the standard's page describing the function?

JMarsch Over a year ago

compiler errors for me -- "std::to_string: ambiguous call to overloaded function"

Sam Goldberg Over a year ago

I would rephrase that to "Finally, we have ...".

tanguy_k · Accepted Answer · 2011-12-02 16:28:01Z

Like mentioned earlier, I'd recommend boost lexical_cast. Not only does it have a fairly nice syntax:

#include <boost/lexical_cast.hpp> std::string s = boost::lexical_cast<std::string>(i);

it also provides some safety:

try{ std::string s = boost::lexical_cast<std::string>(i); }catch(boost::bad_lexical_cast &){ ... }

David Thornley · Accepted Answer · 2008-11-07 22:55:24Z

Not really, in the standard. Some implementations have a nonstandard itoa() function, and you could look up Boost's lexical_cast, but if you stick to the standard it's pretty much a choice between stringstream and sprintf() (snprintf() if you've got it).

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