Getting specific information from a string

[Megum919]

Hey guys, I need help with some idea that I can get specific information from a string.

For example, I got a txt file contents strings like this:

{id:1234567,first:Mary,last:Green,DOB:1996-10-03,GPA:4.0}
{id:1234568,first:Peter,last:White,DOB:1997-05-22,GPA:3.8}
{id:1654238,first:Nick,last:Park,DOB:1995-08-18,GPA:4.0}
{id:1234587,first:Katy,last:Green,DOB:1995-08-18,GPA:4.0}

If I've been asked for information like:
first

then I need to print out:
Mary Peter Nick Katy

Thank you!

[Thomas1965]

You can use getline with ',' as delimiter which will give you a string.
Then check if the string contains first: if yes print everything after the colon.

[lastchance]

#include <iostream>
#include <sstream>
#include <string>
#include <vector>
using namespace std;

vector<string> grab( istream &strm, string tag );

//======================================================================

int main()
{
   stringstream strm( "{id:1234567,first:Mary,last:Green,DOB:1996-10-03,GPA:4.0}\n"
                      "{id:1234568,first:Peter,last:White,DOB:1997-05-22,GPA:3.8}\n"
                      "{id:1654238,first:Nick,last:Park,DOB:1995-08-18,GPA:4.0}\n"
                      "{id:1234587,first:Katy,last:Green,DOB:1995-08-18,GPA:4.0}\n" );

   string tag = "first:";                            // Tag, including semicolon
   vector<string> names = grab( strm, tag );         
   for ( string s : names ) cout << s << " ";
}

//======================================================================

vector<string> grab( istream &strm, string tag )
{
   vector<string> result;
   string line;

   while ( getline( strm, line ) )                   // Read one line
   {
      int p = line.find( tag );                      // Find the start of the tag
         if ( p == string::npos ) continue;          // Ill-formed string; ignore rest of line
      p += tag.size();                               // Get beyond the tag
      int q = line.find_first_of( ",}", p );         // First thing after data
      result.push_back( line.substr( p, q - p ) );   // Add to collection
   }
   return result;
}

//====================================================================== 

Mary Peter Nick Katy