How Do I Do Multiple Searches From A Text File In C++?

Question

1.00/5 (1 vote)

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So, this is the program i tried to write- The user will be given a chance to enter a string and the string will be matched with the string stored in a text file. When, i tried it, it worked fine and showed no problems. Now, i wanted to twist the program a bit and wanted to give the user multiple chances to search for a word from the database. This is where the program started showing me errors. I placed the program in a loop and tried to give the user two times to search for a word in the database. The problem is when i run the program, it only works for the first time the second time and the remaining times it doesn't search for the word in the database. I don't know where the problem is. Please can anyone suggest me anything. Here is my code.
My text file which i am looking for contains the following (Hello World, Hey).

C++

#include <iostream>
#include <fstream>
#include <string>

using namespace std;


int main()
{

  string search,line;
  ifstream read;

  int i =0;

  while(i<2)
  {
    read.open("type.txt");

  cout<<"Enter the word to search"<<endl;
  cin>>search;

  size_t pos;
  if(read.is_open())
  {
	  while (getline(read,line))
	  {
		   pos = line.find(search);
			   if(pos != string::npos)
			  {
				  

				  cout<<line<<endl;
				  
				  

			   }
	  }

	  




	  }

  i++;



  }







  system("pause");







  }

Posted 23-Nov-14 10:57am

Surajit Das

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Comments

PIEBALDconsult 23-Nov-14 17:38pm

Maybe try closing the file?

Surajit Das 23-Nov-14 18:15pm

@PIEBALDconsult- awesome thanks it worked.!

2 solutions

Solution 2

The while loop should test if the ifstream is at eof or an error using good(). getline only returns the file stream not a boolean expression.

int main()
{
string _search;
string line;
ifstream read;

int i =0;
    while(i++<2)
    {
        cout<<"Enter the word to search"<<endl;
        cin>>_search;
        read.open("type.txt");
        size_t pos,i=0;
        if(read.is_open())
        {
            while (read.good())
            {
                i++;
                getline(read,line);
                pos = line.find(_search);
                if(pos != string::npos)
                {
                   cout<<i<<": "<<line<<endl;
                }
                else
                {
                    cout<<"Not found"<<endl;
                }

            }
            read.close();
        }

    }
}

Posted 24-Nov-14 16:37pm

BacchusBeale

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Surajit Das · Accepted Answer · 2014-11-23T12:36:00

Solution 1

C++

#include <iostream>
#include <fstream>
#include <string>

using namespace std;
 

int main()
{
 
  string search,line;
  ifstream read;
 
  int i =0;
 
  while(i<2)
  {
    read.open("type.txt");
 
  cout<<"Enter the word to search"<<endl;
  cin>>search;
 
  size_t pos;
  if(read.is_open())
  {
	  while (getline(read,line))
	  {
		   pos = line.find(search);
			   if(pos != string::npos)
			  {
				  
 
				  cout<<line<<endl;
				  
				  read.close();
 
			   }
	  }
 
	  
 

 

	  }
 
  i++;
 

 
  }
 

 

 

 
  system("pause");
 

 

 

 
  }

Posted 23-Nov-14 12:36pm

Surajit Das

Updated 23-Nov-14 12:37pm

v2

Comments

Sergey Alexandrovich Kryukov 23-Nov-14 18:46pm

Not an answer. You got a solution from a member, but why posting an answer and even self accepting it?
—SA

Surajit Das 23-Nov-14 18:59pm

@SA:- All i did was just updated the solution such that it can help somebody in the future. The member who suggested me the idea was a comment so i couldn't accept his solution. Regarding accepting my solution, it was just for fun!