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, Jul 28 '10 at 22:06
@Zan: Durp. That's what I get for posting code I didn't compile. — Paul Nathan, Jul 28 '10 at 22:13
How about some of the examples from the following: http://www.codeproject.com/KB/recipes/Tokenizer.aspx They are very efficient and somewhat elegant. — , Nov 02 '10 at 05:01
@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, Nov 08 '10 at 17:38

score 136 · Accepted Answer · edited Feb 27 '12 at 19:50

136

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 '12 at 19:50

tanguy_k

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answered Dec 02 '11 at 20:12

Johannes Schaub - litb

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Very spiffy. Have a link to the standard's page describing the function? – Paul Nathan Dec 02 '11 at 23:53
6

compiler errors for me -- "std::to_string: ambiguous call to overloaded function" – JMarsch Oct 12 '12 at 20:06
8

I would rephrase that to "*Finally*, we have ...". – Sam Goldberg Aug 02 '13 at 15:08

score 28 · Answer 2 · edited Dec 02 '11 at 16:28

28

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 &){
 ...
}

edited Dec 02 '11 at 16:28

tanguy_k

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answered Nov 07 '08 at 23:14

Mic

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score 22 · Answer 3 · answered Nov 07 '08 at 22:55

22

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).

answered Nov 07 '08 at 22:55

David Thornley

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Good thing this has been fixed, see [Schaub's answer](http://stackoverflow.com/questions/273908/c-integer-stdstring-conversion-simple-function#8362045) – sehe May 16 '12 at 08:00

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

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