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  1. #include <iostream>
  2. #include <iterator>
  3. #include <algorithm>
  4.  
  5. bool isNumber( const std::string& s )
  6. {
  7.     for( std::string::const_iterator it=s.begin(); it!=s.end(); ++it )
  8.     {
  9.         if( !std::isdigit(*it) ) return false;
  10.     } 
  11.     return true;
  12. }
  13.  
  14. bool printNumbersOnly( std::istream_iterator<std::string>& it )
  15. {
  16.     bool nothing = true;
  17.     std::istream_iterator<std::string> eos;
  18.     while( it != eos )
  19.     {
  20.         if( *it == "end" ) break;
  21.         if( isNumber(*it) )
  22.         {
  23.             nothing = false;
  24.             std::cout << *it << std::endl;
  25.         }
  26.         ++it;
  27.     }
  28.     return !nothing;
  29. }
  30.  
  31. int main() {
  32.     std::istream_iterator<std::string> iit(std::cin);
  33.     if( !printNumbersOnly( iit ) ) std::cout << "nothing\n";
  34.     return 0;
  35. }
Success #stdin #stdout 0s 3036KB
comments (?)
stdin
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I have a 3sons
and1 son and 25dogs
end 
1 he he
stdout
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nothing
https://ideone.com/7TnX7m
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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