what's concise C++ idiom for conversion from int|double to string?

Question

Looking through related Q&A's, it seems that best C++ practice for conversion to string is

ostringstream stringStream;
stringStream << input_value;        // let's say, input_value is a double
output_string = stringStream.str();

Is there any way to achieve the same in less than three lines of clean C++?

Duplicate of http://stackoverflow.com/questions/5590381/easiest-way-to-convert-int-to-string-in-c and http://stackoverflow.com/questions/332111/how-do-i-convert-a-double-into-a-string-in-c — HAL, Aug 23 '13 at 12:15
Put the above three lines in a function, then it'll only take one line. — Crowman, Aug 23 '13 at 12:16
Thanks for the many useful answers! Seems I am allowed to accept only one, that will forcibly be an arbitrary choice, sorry. — Joachim W, Aug 23 '13 at 12:23

score 12 · Accepted Answer · answered Aug 23 '13 at 12:11

12

Using the std::to_string family of functions:

std::string s = std::to_string(3.1416);

If you don't have the required C++11, another option is boost::lexical_cast.

std::string s = boost::lexical_cast<std::string>(3.1416);

answered Aug 23 '13 at 12:11

juanchopanza

score 10 · Answer 2 · answered Aug 23 '13 at 12:11

10

output_string = std::to_string(input_value);

(For C++03, look into boost::lexical_cast).

answered Aug 23 '13 at 12:11

Jesse Good

3

Notice that this is a `C++11` feature – Sebastian Hoffmann Aug 23 '13 at 12:12

score 3 · Answer 3 · answered Aug 23 '13 at 12:12

3

If you don't have C++11, you can use something like:

boost::lexical_cast<std::string>(input_value);

(it's easy enough to write your own to_string if you don't want Boost though - you're really just wrapping your existing code in a function).

If you do have C++11, stick with the std::to_string Jesse Good & juanchopanza already mentioned.

answered Aug 23 '13 at 12:12

Useless

boost is not part of the standard C++. And wrapping everything in a function hiding everything can always be done by anyone, but... it doesn't explain anything – Emilio Garavaglia Aug 23 '13 at 12:16
`to_string` and `lexical_cast` are functions - what's the difference? – Useless Aug 23 '13 at 12:17
to_string and std::stringstream are part of the C++ standard. Boost is not. And if we admit to take elsewhere delivered functions, we are playing a different game. – Emilio Garavaglia Aug 23 '13 at 12:22

score 0 · Answer 4 · answered Aug 23 '13 at 12:15

0

Both are one-liners in C++ 11:

std::string s1 = std::to_string(42);

and

std::string s2 = std::to_string(42.0);

answered Aug 23 '13 at 12:15

Sergey K.

4 Answers4