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-   -   c++ file string from text file into 1d array (https://www.linuxquestions.org/questions/programming-9/c-file-string-from-text-file-into-1d-array-404637/)

ak3 01-17-2006 04:53 PM

c++ file string from text file into 1d array
 
i need help in C++ arrays

i have a text file with

David (name)
1 ( some variable )
bowler
2 (stats)
3
4

i can read the file in and store them into a 1d array however it stores each character in one element when i want to have each line in one element. please can any one help asap thanks

code already:

#include <stdlib.h>
#include <iostream>
using namespace std;
#include<string>
#include<string.h>
#include<fstream>
#include<iomanip>

using std::setw;
#include <conio.h> //For getch function
using std::cout;
using std::endl;


const int N = 10;

ofstream FOut; //File Out
ifstream FIn; //File In
string File; //File Name

void main()
{
/
char arr[N], *p;

cout <<"Enter file name:"<<endl;
cin >> File;
FIn.open( File.c_str() );


for(int i = 0; i<N; i++)

{


FIn >> arr[i];

}

cout << *(arr) << "";


}

graemef 01-17-2006 04:56 PM

Store each line in a C++ string. The problem with character arrays is that you need to know their size at compile time.

graeme.

Hivemind 01-17-2006 06:16 PM

Code:

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

int
main()
{
  std::cout << "Enter filename: ";

  std::string filename;

  cin >> filename;

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

  if(!file)
  {
      std::cerr << "Error opening file " << filename << std::endl;

      return EXIT_FAILURE;
  }

  std::string line;
  std::vector<std::string> contents_of_file;

  while(getline(file, line))
  {
      contents_of_file.push_back(line);

      std::cout << "Read line " << line << std::endl;
  }
}


ak3 01-17-2006 07:18 PM

Thanks for your reply Hivemind and graeme.

the code runs fine Hivemind, however i need it to be stored in a 1d array as i will need access to the elements, throughout the program. i need to make comparsions with the elements to other arrays i have

Hivemind 01-17-2006 07:31 PM

The vector I used is one-dimensional..a two dimensional vector would be a vector of vectors of some tyoe.

ak3 01-17-2006 10:04 PM

oh ok i see, sorry stupid question i am quite new to c++. to print out one line of the txt file would i have a counter then increment it with line? or how could the vector just point to a particular line in the text file

Hivemind 01-18-2006 02:36 AM

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

int
main()
{
std::cout << "Enter filename: ";

std::string filename;

cin >> filename;

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

if(!file)
{
std::cerr << "Error opening file " << filename << std::endl;

return EXIT_FAILURE;
}

std::string line;
std::vector<std::string> contents_of_file;

while(getline(file, line))
{
contents_of_file.push_back(line);

std::cout << "Read line " << line << std::endl;
}

std::cout << "Read " << contents_of_file.size() << " lines from the file." << std::endl;
std::cout << "Any particular line is accessed using contents_of_file[line_number-1]."
<< std::endl;

}

ak3 01-18-2006 07:27 AM

so if i wanted the line two to be printed i would have this code line:
std::cout << contents_of_file[line_number-1];

line_number has to be declared first to which value

Hivemind 01-18-2006 07:36 AM

If you read ten lines into the vector they have indexes 0-9. So if you want the first line, the index should be 0, the last the index would be nine, the fifth the index would 4. line number - 1...

ak3 01-19-2006 11:34 AM

i have stored a vector in a class, how do i get access to it from another class?

graemef 01-19-2006 02:22 PM

It depends if you made the vector public, private or protected.

If it is public then you can access directly via an object of that class
Code:

myObj.theVector[0];    // as an object
myObjPtr->theVector[0]; // as a pointer to the object

If the vector is either private or protected then it is best to write an access method
Code:

myObj.getVector(0);
and the access method will return the appropriate element of the vector (maybe checking that the element actually exists)

I hope that helps a little.

graeme.

ak3 01-19-2006 10:14 PM

thanks for the tip,

I have a vector vector<string> the; set up in a class as public
then in another class what would i do to get access to it. would i have to use a pointer in the first class and then get reference to it?
public:
myObj.the;
myObjPtr->the[0];






thanks
graeme

Hivemind 01-20-2006 04:22 AM

Just write a simple access method.

Code:

/* class holding a vector with access method, only important bits shown */
class MyClass
public:
  std::string get_element_in_vector(unsigned short index)
  {
      if(index > the_vector.size())
        throw std::runtime_error("Index out of bounds");

      return the_vector[index]; /* Only reached for valid indexes. */
  }
private:
  std::vector<std::string> the_vector;
};

Call it like you call any non-static member function. You can catch the return
value in const string reference if you dont need to modify it to speed up performance.
Code:

MyClass myinst;

/* Do stuff with myinst, like populating the vector. */

/* I dont need to modify str, so I catch it in a const reference */
const std::string& str = myinst.get_element_in_vector(some_valid_index);

/* str2 to I need to modify, so: */
std::string str2 = myinst.get_element_in_vector(another_valid_index);


ak3 01-20-2006 06:41 AM

i got two classes, 1 class has a vector where values are read in, i want a 2nd class to access the vector from class 1 to check the values in the a particlar element. the main cpp file will call these functions.
how would i go about this? i can't seem to access the vector in another class, and when i do it doesn't display anything. even though i have something in the vector

any ideas?

Hivemind 01-20-2006 07:04 AM

I just showed you...


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