C++ Parsing problem

[KARAMVIR_SINGH_RAJPA]

Code for extraction of word and links from the string

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <sstream>
#include <string>

using namespace std;

void parsefunc(ifstream& ifile, ofstream& ofile)
{

string input;
//vector <char> input;

    
   //bool recordingbracket = false;
   
   string linkname;
   
 while (ifile.fail() == false) // as long as there is an input
 {
 
   char ab = ifile.get();
   if (ifile.fail()  == true)
   {
   break;
   }
        // cout<<ab;
   
   if ((ab >= 65 && ab<= 90) || (ab >= 97 && ab <= 122))
      {
      
        // input.push_back(ab);
        stringstream chr;
            chr<<ab; // char variable to a string
            input = input + ab;
      }
      
      else if (ab == ' ')
      {
      
      if (input[input.size()-1] != '\n' )
      {
         
      
         // input.push_back('\n');
         input = input + '\n';
      }
      }
      
      else if (ab== '(' || ab== '[' )
      {
        // input.push_back("LINK");
        
        if ( ab == '(')
        {
            input = input + "LINK (";
            string link;
            
          while (ifile.fail() == false)
          {
            char abb =  ifile.get();
               if (abb !=')')
               {
                  stringstream abs;
            abs<<abb;
            link = link + abb;
            
               } 
               else
               {
                  break;
               }
            
             
          }
          if(linkname == "")
          {
            linkname  = link;
          }
            input = input + link+ "," +linkname + ")";
        }
        else {
        

         linkname =  "";
            
            
            
         while (ifile.fail() == false)
          {
            char abb =  ifile.get();
               if (abb !=']')
               {
                  stringstream abs;
            abs<<abb;
            linkname = linkname + abb;
            
               } 
               else
             
               {
                   abb =  ifile.get();
                   if( abb != '(')
                   {
                   input  = input + linkname;
                     break;
                   }
                   else
                   {
                      input = input + "LINK (";
            string link;
            
          while (ifile.fail() == false)
          {
            char abb =  ifile.get();
               if (abb !=')')
               {
                  stringstream abs;
            abs<<abb;
            link = link + abb;
            
               } 
               else
               {
                  break;
               }
            
             
          }
          if(linkname == "")
          {
            linkname  = link;
          }
            input = input + link+ "," +linkname + ")";
                   }
                  break;
               }
         }
         }
        

          
         
         
      
      }
 
}

  /* for (int i =0; i< input.size(); i++)
   {
      cout<<input[i];
      
   } */
   //cout<<input;
   ofile<<input;
   } 

int main(int argc , char* argv[])
{
  if(argc < 3 ){
    cerr << "Please provide an input and output file" << endl;
    return 1;
  }

  ofstream ofile(argv[2]);
  ifstream ifile(argv[1]);
  //int len = atoi(argv[1]);
  parsefunc(ifile, ofile);
  ofile.close();
  ifile.close();
  return 0;
}

This code is not working for all cases. Anyone kindly help me out.