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  1. #include <string>
  2. #include <sstream>
  3. #include <iostream>
  4.  
  5. int main()
  6. {
  7.     // open the stream which contains the city data
  8.     // (this example uses a stringstream instead of a filestream)
  9.     std::istringstream stm( R"(
  10. A|City1|Data.1|Data.2|Data.3
  11. R|01R|Data.4|Data.5|Data.6
  12. R|02R|Data.4|Data.5|Data.6
  13. R|03R|Data.4|Data.5|Data.6
  14. R|04R|Data.4|Data.5|Data.6
  15.  
  16. A|City2|Data..1|Data..2|Data..3
  17. R|01R|Data..4|Data..5|Data..6
  18. R|02R|Data..4|Data..5|Data..6
  19. R|03R|Data..4|Data..5|Data..6
  20. R|04R|Data..4|Data..5|Data..6
  21.  
  22. A|City3|Data...1|Data...2|Data...3
  23. R|01R|Data...4|Data...5|Data...6
  24. R|02R|Data...4|Data...5|Data...6
  25. R|03R|Data...4|Data...5|Data...6
  26. R|04R|Data...4|Data...5|Data...6
  27.  
  28.                           )" ) ;
  29.  
  30.    // get the city name
  31.    std::string city_name = "City2" ;
  32.  
  33.    // we need to look a line starting with
  34.    // the city_name prefixed by "A|" and suffixed by '|'
  35.    const std::string search_string = "A|" + city_name + '|' ;
  36.  
  37.    // read and discard lines from the stream
  38.    // till we get to a line starting with the search_string
  39.    std::string line ;
  40.    while( std::getline( stm, line ) && line.find(search_string) != 0 ) ;
  41.  
  42.    // check if we have found such a line, if not report an error
  43.    if( line.find(search_string) != 0 )
  44.    {
  45.        std::cerr << "city '" << city_name << " was not found\n" ;
  46.        return 1 ;
  47.    }
  48.  
  49.    // we need to form a string that would include the whole set of data
  50.    // based on the selection of City
  51.    std::string result = line + '\n' ; // result initially contains the first line
  52.  
  53.    // now keep reading line by line till we get an empty line or eof
  54.    while( std::getline( stm, line ) && !line.empty() )
  55.       result += line + '\n' ; // append this line to the result
  56.  
  57.    // use the result (in this example, we just print it out)
  58.    std::cout << "data for '" << city_name << "'\n--------------\n" << result ;
  59. }
  60.  
Success #stdin #stdout 0s 3476KB
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stdin
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Standard input is empty
stdout
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data for 'City2'
--------------
A|City2|Data..1|Data..2|Data..3
R|01R|Data..4|Data..5|Data..6
R|02R|Data..4|Data..5|Data..6
R|03R|Data..4|Data..5|Data..6
R|04R|Data..4|Data..5|Data..6
https://ideone.com/TcAGNJ
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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