Re: Converting a substring to Integer

From:
"Daniel T." <daniel_t@earthlink.net>
Newsgroups:
comp.lang.c++
Date:
Tue, 05 Feb 2008 20:35:34 -0500
Message-ID:
<daniel_t-B65032.20353405022008@earthlink.vsrv-sjc.supernews.net>
Reetesh Mukul <reetesh.mukul@gmail.com> wrote:

You can try this:-

#include <iostream>
#include <sstream>
#include <cctype>

int main()
{
  std::string s = "dsdhjsahdk dsdjdsaj 36782367 sdjdhak";

  int j = 0;
  std::stringstream cstr;
  cstr << s;
  int i = 0;
  char ch;

  while( cstr >> ch )
    {
      if( std::isdigit(ch) )
    {
      cstr.putback(ch);
      break;
    }

From here:

      if( ( j = s.find(" ",j) )== std::string::npos )
    {
      cstr.seekg(-1);
      break;
    }

      cstr.seekg(++j, std::ios::beg);

to here. Is this block of code necessary?

    }

  if(cstr)
    {
      cstr >> i;
    }
  std::cout << i;

  return 0;
}


Wouldn't this be a simpler way of doing the same thing?

int main()
{
   std::string s = "dsdhjsahdk dsdjdsaj 36782367 sdjdhak";

   int i = 0;
   std::stringstream cstr( s );
   char ch = 0;
   while( cstr >> ch && !isdigit( ch ) )
   { }
   cstr.putback( ch );
   cstr >> i;
   cout << i;
}

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