itoa to std::to_string

Question

This may be a vaugue question but im getting this error

Simulator.cpp: In member function `void Simulator::generatePassengers()': 
Simulator.cpp:60: error: `itoa' undeclared (first use this function)

This is the code im having an issue with

itoa(i,buf,10);

What can i use to fix this issue because on one compiler i get this issue on another i dont. So im stumped here has to work on both.

    char buf[3];
    if(i<10)
    {
        key1.append("0");
        key2.append("0");
        key3.append("0");
    }
    itoa(i,buf,10);
    key1.append(buf);
    key2.append(buf);
    key3.append(buf);

As above, the following may be useful http://stackoverflow.com/questions/6920554/source-code-in-embedded-c-for-unsigned-integer-to-string depending on your exact requirements — PeterJ, Dec 29 '12 at 04:45
What's wrong with `to_string`, `stringstream`,or `boost::lexical_cast`? — Pubby, Dec 29 '12 at 04:45
@Cheersandhth.-Alf `boost::lexical_cast` is 100% predictable and faster than most other formatting options for just about any conversion. http://www.boost.org/doc/libs/1_52_0/doc/html/boost_lexical_cast/performance.html — David Stone, Dec 29 '12 at 05:12
@DavidStone: that's a bit of bullshit. e.g. for simple conversion string to `int` i get a factor of 8 to 9 faster than `lexical_cast`, with just an off-the-cuff implementation (no special optimization of that code). **[try the source code yourself](https://gist.github.com/4404935)**. — Cheers and hth. - Alf, Dec 29 '12 at 06:23
I guess I was wrong on that. I fiddled with the code a little bit, and `boost::lexical_cast` was still safer for large values, but when I corrected your code to check for that (and accepted the input number as a command-line argument rather than a compile-time constant), my times were Do it yourself: 2.21 seconds -- boost: 5.98 seconds. That was for the greatest `int` value. Now, my changes have the slight disadvantage of rejecting the least `int` value (which I guess is still better than undefined behavior), but I'm sure I could add that in without tripling execution time. — David Stone, Dec 29 '12 at 19:18
I tried compiling with BOOST_LEXICAL_CAST_ASSUME_C_LOCALE, and it did speed it up to 4.31 seconds instead of 5.98, but that's still twice as slow as the manual version. Just as a note, my system that I tested is gcc 4.7.2 with boost 1.48.0. I will have to check back with the latest Boost to see if they have fixed any of these problems. — David Stone, Dec 29 '12 at 19:21

score 3 · Answer 1 · answered Dec 29 '12 at 04:51

3

Your platform doesn't have itoa. It's not specified by any standard. You can use any replacement you like, including printf or just writing your own.

answered Dec 29 '12 at 04:51

David Schwartz

179,497
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score 3 · Accepted Answer · answered Dec 29 '12 at 04:52

3

Does this work?

#include <string>
std::string buf = std::to_string(i);
key1.append(buf);
key2.append(buf);
key3.append(buf);

answered Dec 29 '12 at 04:52

soniccool

5,790
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98

itoa to std::to_string

2 Answers2