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Old 01-17-2006, 04:53 PM   #1
ak3
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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) << "";


}
 
Old 01-17-2006, 04:56 PM   #2
graemef
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Store each line in a C++ string. The problem with character arrays is that you need to know their size at compile time.

graeme.
 
Old 01-17-2006, 06:16 PM   #3
Hivemind
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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;
   }
}
 
Old 01-17-2006, 07:18 PM   #4
ak3
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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
 
Old 01-17-2006, 07:31 PM   #5
Hivemind
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The vector I used is one-dimensional..a two dimensional vector would be a vector of vectors of some tyoe.
 
Old 01-17-2006, 10:04 PM   #6
ak3
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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

Last edited by ak3; 01-17-2006 at 10:13 PM.
 
Old 01-18-2006, 02:36 AM   #7
Hivemind
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#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;

}
 
Old 01-18-2006, 07:27 AM   #8
ak3
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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
 
Old 01-18-2006, 07:36 AM   #9
Hivemind
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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...
 
Old 01-19-2006, 11:34 AM   #10
ak3
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i have stored a vector in a class, how do i get access to it from another class?
 
Old 01-19-2006, 02:22 PM   #11
graemef
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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.
 
Old 01-19-2006, 10:14 PM   #12
ak3
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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

Last edited by ak3; 01-20-2006 at 04:29 AM.
 
Old 01-20-2006, 04:22 AM   #13
Hivemind
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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);

Last edited by Hivemind; 01-20-2006 at 04:23 AM.
 
Old 01-20-2006, 06:41 AM   #14
ak3
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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?
 
Old 01-20-2006, 07:04 AM   #15
Hivemind
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I just showed you...
 
  


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