Finding a string in a text file and displaying the entire line in c++

Question

I want my program to look for a student's name in a text file and then display that particular line.

I'm just getting the first line of the text file as output and not the line I'm looking for.

void OTHERS::search_acc()
{
  string srch;
  string line;

  fstream Myfile;
  Myfile.open("STUDENTS", ios::in|ios::out);
  cout << "\nEnter Student Name: ";
  cin.ignore();
  getline(cin, srch);

  if(Myfile.is_open())                                //The problem is in this if block
  {
      getline(Myfile, line);
      line.find(srch, 0);
      cout << "\nSearch result is as follows: \n" << line << endl;
  }
  else
  {
    cout << "\nSearch Failed...  Student not found!" << endl;
    system("PAUSE");
  }  
}

Also, is it possible to return the location of the string I'm looking for in the text file?

Does this answer your question? Read File line by line to variable and loop — Object object
– Object object, Commented Apr 14, 2020 at 17:11
Right idea, but the selected answer in that dupe doesn't really read line by line. — user4581301
– user4581301, Commented Apr 14, 2020 at 17:14
@cigien Can you please explain it explicitly through a code? — DC007744
– DC007744, Commented Apr 14, 2020 at 17:19
@LonesomeParadise I want to display just one particular line. The suggested solution explains how to print every line. — DC007744
– DC007744, Commented Apr 14, 2020 at 17:22

cigien · Accepted Answer · 2020-04-14 17:22:40Z

3

You need to read all the lines in a loop, and search in each one of them, e.g.

if(Myfile.is_open())
{
  while(getline(Myfile, line))                 // read all the lines
    if (line.find(srch) != std::string::npos)  // search each line
      cout << "\nFound on this line: \n" << line << endl;
}

answered Apr 14, 2020 at 17:22

cigien

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Comments

Umar Farooq · Accepted Answer · 2020-04-14 17:16:16Z

-1

int line=0;
while(!Myfile.eof()){
    getline(Myfile, line);
    line.find(srch, 0);
    ++line;
}
//this line will tell you the line number
cout << "\nSearch result is as follows: \n" << line << endl;

you are reading one line read the whole file

edited Apr 14, 2020 at 17:16

answered Apr 14, 2020 at 17:13

Umar Farooq

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1 Comment

user4581301 Over a year ago

Recommended reading: Why is iostream::eof inside a loop condition (i.e. while (!stream.eof())) considered wrong?

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