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Mar 6th, 2007

Reading from text file into array

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Hi i'm pretty new to C++ (well very new!) and i need to read the information from a text file into an array. The kind of data i'll be using is a simple list of names. This is my first attempt at;

c Syntax (Toggle Plain Text)
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
 
int main () 
{
  string array[5];                          // creates array to hold names
  short loop;                               //short for loop for input
  short loop2;                               //short for loop for output
  string line;                              //this will contain the data read from the file
  ifstream myfile ("example.txt");          //opening the file.
  if (myfile.is_open())                     //if the file is open
  {
    while (! myfile.eof() )                 //while the end of file is NOT reached
    {
      getline (myfile,line);                //get one line from the file
      cout << line <<  endl;                //and output it
        for (loop=0; loop<5;loop++)         //criteria for input loop (as array 0-5)
      {
      array[loop]=line;                     //output loop statement
      };
        for (loop2=0; loop2<5;loop2++)      //criteria for output loop (as array 0-5)
      {
      cout << array[loop2];                     //loop statement
      };
    }
    myfile.close();                         //closing the file
  }
  else cout << "Unable to open file";       //if the file is not open output 
  system("PAUSE");
 
 
       system("PAUSE");
  return 0; 
}
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main () 
{
  string array[5];                          // creates array to hold names
  short loop;                               //short for loop for input
  short loop2;                               //short for loop for output
  string line;                              //this will contain the data read from the file
  ifstream myfile ("example.txt");          //opening the file.
  if (myfile.is_open())                     //if the file is open
  {
    while (! myfile.eof() )                 //while the end of file is NOT reached
    {
      getline (myfile,line);                //get one line from the file
      cout << line <<  endl;                //and output it
        for (loop=0; loop<5;loop++)         //criteria for input loop (as array 0-5)
      {
      array[loop]=line;                     //output loop statement
      };
        for (loop2=0; loop2<5;loop2++)      //criteria for output loop (as array 0-5)
      {
      cout << array[loop2];                     //loop statement
      };
    }
    myfile.close();                         //closing the file
  }
  else cout << "Unable to open file";       //if the file is not open output 
  system("PAUSE");
    

       system("PAUSE");
  return 0; 
}

The data appears in a file that looks like this:
john
dave
paul
jack
adam

Thanks for your time.

Last edited by WaltP; Mar 6th, 2007 at 12:13 pm. Reason: Added CODE tags. Read the words on the input box background

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stanwaka

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Mar 6th, 2007

Re: Reading from text file into array

Use [ code ] [/ code ] (without spaces) tags to post your code.

Is this what you want....
You can simultaneously read line and put it into array[] and line, so you dont need two loops.

C++ Syntax (Toggle Plain Text)
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
 
int main ()
{
    string array[5]; // creates array to hold names
 
    short loop=0; //short for loop for input
 
    string line; //this will contain the data read from the file
    ifstream myfile ("example.txt"); //opening the file.
    if (myfile.is_open()) //if the file is open
    {
        while (! myfile.eof() ) //while the end of file is NOT reached
        {
            getline (myfile,line); //get one line from the file
            array[loop] = line;
            cout << array[loop] << endl; //and output it
            loop++;
        }
        myfile.close(); //closing the file
    }
    else cout << "Unable to open file"; //if the file is not open output
 
    system("PAUSE");
    return 0;
}
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main ()
{
    string array[5]; // creates array to hold names

    short loop=0; //short for loop for input

    string line; //this will contain the data read from the file
    ifstream myfile ("example.txt"); //opening the file.
    if (myfile.is_open()) //if the file is open
    {
        while (! myfile.eof() ) //while the end of file is NOT reached
        {
            getline (myfile,line); //get one line from the file
            array[loop] = line;
            cout << array[loop] << endl; //and output it
            loop++;
        }
        myfile.close(); //closing the file
    }
    else cout << "Unable to open file"; //if the file is not open output

    system("PAUSE");
    return 0;
}

Last edited by vishesh; Mar 6th, 2007 at 6:34 am.

vishesh

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Mar 6th, 2007

Re: Reading from text file into array

Thats it! Thanks alot Vishesh!

stanwaka

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Mar 6th, 2007

Re: Reading from text file into array

Problem #1:

C++ Syntax (Toggle Plain Text)
while (! myfile.eof() )     //while the end of file is NOT reached
while (! myfile.eof() )     //while the end of file is NOT reached

See this (.eof() is identical to feof()

Problem #2:

C++ Syntax (Toggle Plain Text)
system("PAUSE");
system("PAUSE");

See this

WaltP

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Mar 6th, 2007

Re: Reading from text file into array

Vishesh, like Walter said, don't use EOF or you just end up writing an additonal condition to prevent the fetching of the last record, one too many times.

Instead use, while ( getline (file_stream, my_string ).good () )

And as for system ( "PAUSE" ) read the article posted.

Last edited by ~s.o.s~; Mar 6th, 2007 at 12:47 pm.

~s.o.s~

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Dec 10th, 2008

Re: Reading from text file into array

(Toggle Plain Text)

#include <iostream> //For Input/Output
#include <fstream> //For File Input/Output
#include <string> //For Saving The Line Into The Array
using namespace std;
int main ()
{
	string array[5]; //Array to save the line on
	int loop=0; //Index of array
	int loop2;
	string line; //The line taken from the *.txt source
	ifstream myfile ("example.txt"); //To read from the *.txt File
	if (myfile.is_open()) //Checking if the file can be opened
	{
		while (! myfile.eof() ) //Runs while the file is NOT at the end
		{
			getline (myfile,line); //Gets a single line from example.txt
			array[loop]=line; //Saves that line in the array
			loop++; //Does an increment to the variable 'loop'
		}
		myfile.close(); //Closes the file
	}
	else cout << "Unable to open file"<<endl; //Gives that sentence if the file can't be opened
	for(loop2=0;loop2<=loop;loop2++) //For loop make to cout the lines stored
		cout<<array[loop2]<<endl;    //inside of the variable 'array'
	return 0;
}

Your code made the 5 lines as output on the command prompt, but only the first line was saved in the variable array.

My code as I edited yours, saves the 5 lines from the file into the array and then it outputs them. Hope you benefit from this.

=EDIT= I'm sorry, I didn't see that you posted a corrected code before me. I didn't continue the rest of the thread. So sorry

Last edited by hannad; Dec 10th, 2008 at 8:57 am.

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