How to check for a word in a txt file line by line and when found print the whole line?

Question

1.00/5 (1 vote)

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To check for a word in a text file line by line and when found print the whole line which is containing the word .Pleas help as fast as possible.

What I have tried:

here is the code:-
Here cw is a pointer having the line stored in it,w is the word to be searched for, gw is also a pointer used to store the word obtained from each line.

while (!o.eof())
{
o.getline(cw,'\n');
for(i=0;cw[i]!='\0';i++)
{
gw[i]=cw[i];
}
// if(cw[i]==w[i])
if(gw==w)
cout<<cw;
if(o.eof())break;
}
o.close();

Posted 14-Nov-18 1:55am

Vishal Banerjee

Updated 16-Jan-21 20:45pm

v2

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2 solutions

Solution 2

C++

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
  ifstream ifs("in.txt");

  string word = "foo";
  string line;

  while( getline(ifs, line ))
  {
    size_t pos = line.find(word);
    if ( pos != string::npos)
      cout << line << endl;
  }
}

[update]
If you don't want foofighters, that is if you need to search your word between word-boundaries (as hinted by yourself and KarstenK) then you might use a regular expression:

C++

#include <iostream>
#include <fstream>
#include <regex>
using namespace std;

int main ()
{
  ifstream ifs("in.txt");

  string word = "foo";

  std::regex e{"\\b" + word + "\\b"};

  string line;

  while( getline(ifs, line ))
  {
    if ( regex_search( line, e) )
      cout << line << endl;
  }
}

[/update]

Posted 14-Nov-18 2:46am

CPallini

Updated 19-Nov-18 1:38am

v2

Comments

KarstenK 14-Nov-18 9:33am

The code may have some flaw like, when searching for "foo" and matching the maysterious "foofigthers" ;-)

CPallini 14-Nov-18 12:21pm

I am aware of it. As a matter of fact, it is by design, you know, it is a feature. :-D

Vishal Banerjee 21-Nov-18 4:50am

Thank you very much for the code help and support but I want to mention here that I am unable to check this code as my compiler is not supporting this feature.

CPallini 21-Nov-18 13:34pm

Apparently you need a more modern compiler.

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Aydin Homay · Accepted Answer · 2018-11-14T02:03:00

Solution 1

Hi,

I wrote a little function in C++ to solve your problem. Please check it out and if it worked press that little green button to accept the solution.

C++

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

int main()
{
	std::cout << "Write the path of the file\n";
	std::string path;
	std::cin >> path;

	std::ifstream file(path.c_str());

	if (file.is_open())
	{
		std::cout << "File '" << path << "' opened.\n";

		std::cout << "Write the word you're searching for\n";
		std::string word;
		std::cin >> word;
		std::string line;

		std::string candidate;

		while (!file.eof()) // for each candidate word read from the file 
		{
			std::getline(file, line);
			std::size_t found = line.find(word);
			if (found != std::string::npos)
				std::cout << "The word '" << word << "' has been found in line " << line;
		}
		file.close();
	}

	else
	{
		std::cerr << "Error! File not found!\n";
		return 1;
	}
}

If this did not solve your problem then please leave a comment and I will assist you by improving my solution until your problem gets solved.

Cheers,
AH

Posted 14-Nov-18 2:03am

Aydin Homay

Updated 19-Nov-18 0:13am

v3

Comments

Vishal Banerjee 15-Nov-18 3:11am

Sorry Sir I am unable to understand the solution.

Vishal Banerjee 15-Nov-18 5:19am

Sir the code provided by you is having error in its first line only the first header file is not supported by the compiler.

Aydin Homay 15-Nov-18 5:21am

I wrote the code in Visual Studio so if you open it there it will work otherwise you need to replace that header. Could you please let me know which editor are you using?

Vishal Banerjee 19-Nov-18 5:12am

Sir please reply.

Vishal Banerjee 16-Nov-18 5:09am

Sir, I am use turbo c++, Dev c++ and code blocks 16.01 only pls try to make the code compatible accordingly.

Aydin Homay 16-Nov-18 7:08am

Remove #include "stdafx.h"

Vishal Banerjee 17-Nov-18 4:52am

Thank you Sir for your response the code is now working but I am not getting the format of entering the "path" in the output screen. Please help.

Vishal Banerjee 17-Nov-18 5:09am

Sir the problem has been solved thank you very much.

Aydin Homay 17-Nov-18 8:49am

Ok good to hear that just please do not forget to press that green accept button ;-) this will help others to hunt the solution easily

Vishal Banerjee 18-Nov-18 3:19am

Sir I have a doubt regarding the code:-
I am not getting the point ""std::string candidate;""
please explain.

Vishal Banerjee 18-Nov-18 6:26am

Sir,
I have found a serious issue in this code so I am rejecting the solution for now but once it is solved I would soon accept it.
The problem is when I am searching for a word like "Cat" words like "Cataract" and all other words beginning with "Cat" are also coming as output. Please solve this out.