converting string to int

Hi Experts,

Is there a secure way of converting string to int.  I can use atoi( ) but, I am not sure if this is secure.
ambuliAsked:
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Kent OlsenDBACommented:
Hi ambuli,

What do you mean by "secure"?

Converting a string to an integer is very straight-forward.  Several functions are available to do that, including atoi(), as you've mentioned.


Kent
evilrixSenior Software Engineer (Avast)Commented:
Sticking with native C, you could use strtol but it doesn't really offer any advantaged over atoi in terms of being more secure.

If you are using C++ you can use a ostringstream to perform the conversion.

// something like this...
std::string s = "1223";
std::ostringstream ss(s);
int i;
ss >> i;

If you're using Boost then you can use lexical_cast. This offers a very simple and safe way to cast between types.

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evilrixSenior Software Engineer (Avast)Commented:
Incidentally, when you say secure I took that to mean a method that avoids the possibility of a buffer over-run in case the string isn't null terminated? If you are using C++ with std::string you should stick to using ostringstream or lexical_cast and that will not be an issue.
ambuliAuthor Commented:
Thank you.  Yes, I was concerned about overruns.
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