From: bop@gmb.dk   
      
   Helmut Jarausch skrev 2012-04-26 23:24:   
   > Hi,   
   >   
   > is there a recommend way to read from an ifstream if this is possibly   
   > empty?   
   >   
   > The simple way   
   >   
   >    std::ifstream  Inp("Empty");   
   >   
   >    if ( ! Inp ) {   
   >      cerr<<  "Open failed\n";   
   >      return 1;   
   >    }   
   >   
   >    int V;   
   >   
   >    while (Inp) {   
   >      cerr<<  "--- here with while ---\n";   
   >      Inp>>  V;   
   >    }   
   >   
   > is invalid, since it enters the while loop at least once (for an empty   
   > file)   
   > The working alternative   
   >   
   >    while (Inp) {   
   >      if ( ! Inp ) break;   
   >     ....   
   >    }   
   >   
   > is ugly.   
   >   
   > Is there a recommended, readable way to do this?   
   >   
      
   The standard way to do this is   
      
        while (Inp >> v) {   
          cerr<<  "--- here with while ---\n";   
          // do something with v   
        }   
      
   which terminates the while loop when the read fails. You don't know the   
   status until you have attempted to do the read.   
      
      
   Bo Persson   
      
      
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