string - Reading from file in C++, dealing with blanks -

i tying read text file in c++98. has pattern, field empty:

id name grade level   1 80 2 b    b 3 c 90 

how can read file such can ignore blanks? ( wish use regex: \d*)

is there simple way of doing that?

you need use knowledge have input make assumptions missing. can use std::stringstream parse individual terms text line. in other words std::stringstream deals blanks ignoring spaces , getting complete term only, example std::stringstream("aaa bbb") >> >> b load strings a "aaa" , b "bbb".

here example program parses input, making robust parser scratch can difficult, if input strict , know expect can away simple code:

#include <iostream> #include <fstream> #include <string> #include <sstream>  //----------------------------------------------------------------------------- // holds data entry struct entry {     int id;     std::string name;     int grade;     std::string level;      entry() {         // default values, if missing.         id = 0;         name = "unknown";         grade = 0;         level = "?";     }      void parsefromstream( std::stringstream &line ) {          std::string s;         line >> s;          if( s[0] >= '0' && s[0] <= '9' ) {             // number, id.             id = atoi( s.c_str() );              // next term             if( line.eof() ) return;             line >> s;         }          if( s[0] >= 'a' && s[0] <= 'z' || s[0] >= 'a' && s[0] <= 'z' ) {             // letter, name             name = s;              // next term             if( line.eof() ) return;             line >> s;          }          if( s[0] >= '0' && s[0] <= '9' ) {             // number, grade             grade = atoi( s.c_str() );              // next term             if( line.eof() ) return;             line >> s;          }          // last term, must level         level = s;     }  };  //----------------------------------------------------------------------------- int main(void) {     std::ifstream input( "test.txt" );      std::string line;     std::getline( input, line ); // (ignore text header)      while( !input.eof() ) {         entry entry;          std::getline( input, line ); // skip header         if( line == "" ) continue; // skip empty lines.          entry.parsefromstream( std::stringstream( line ));          std::cout << entry.id << ' ' << entry.name << ' ' <<                       entry.grade << ' ' << entry.level << std::endl;      }      return 0; }