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From: Ian Collins <ian-news@hotmail.com>
Newsgroups: comp.lang.c++
Subject: Re: What's the most secure way to read a long int ?
Date: Sat, 13 Aug 2011 21:20:07 +1200
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On 08/13/11 09:12 PM, Julien wrote:
> Hello,
>
> I used cppcheck to detect problems and had this :
> (warning) scanf without field width limits can crash with huge input data
>
> void read_cputime(double&  cpu) {
>       long int c;
>       cpu = 0;
>       FILE* f = fopen(CPU_TIME, "r");
>       if (!f) return;
>       int n = fscanf(f, "%ld",&c);<-- pb detected
>       fclose(f);
>       if (n != 1) return;
>       cpu = c;
> }
>
> First I thought about adding a number in the format :
> int n = fscanf(f, "%4ld",&c);
>
> But I want the code to be portable (it must ok for 32 bits or 64 bits).
> So what to use ? A macro ? A c++ const ? C++ internal library (cin ?) ?
> other ?

Do it the C++ way:

   std::ifstream f( CPU_TIME );
   if (!f) return;

   long c;
   f >> c;

   if(!f) return;

-- 
Ian Collins