Problems with sorting

I am trying to sort these 2 lines that I have in a .txt file:

ABC,3
DEF,2

I want it to sort it in Ascending order so it will look like this:

DEF,2
ABC,3

With the code below it is doing a sort that look like this(with a blanc space also ?):

ABC,2

DEF,3

One problem that I have is that the first thing I am reading in is a string and the second an int. So I am using 2 different vectors for these, (string and int).
This is why the output look like this. It is logic for me.

So what do I have to add or change in the code to make it look like:
DEF,2
ABC,3

(The sorting will be made on the integers in ascending order)

Code:

---

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <sstream>
#include <string> 
#include <vector>
#include <cmath>
#include <algorithm>

using namespace std;
int main ()
{
       
       
        char Comma;
        std::string Symbol;
        int Action = 0;
        int Date1 = 0;
        int Date2 = 0;

        int Number = 0;
        int t = 0;

        std::vector<std::vector<int> > Values(3, std::vector<int>(10));
        std::vector<std::vector<string> > Values2(1000, std::vector<string>(10));

        ofstream Sort1;
 
        Sort1.open ("Sort1.txt");
        ifstream Sort ("Sort.txt");

        while        (    getline(Sort, Symbol, ',')  )                         
        {
                t = (t + 1);                // Count
               
                Sort >> Action;                // Buy
                {
                        Values2[t][1] = Symbol;
                        Values[t][2] = Action;
                       
                }
        }

        std::sort(Values.begin(), Values.end());

                for (int Rowsen = 1; Rowsen < (t + 1); Rowsen++)                        //Number of Lines

                {
                        Sort1 <<
                        Values2[Rowsen][1] << ',' <<
                        Values[Rowsen][2]
                        << "\n";
                }

                return 0;
}

---

You probably want to store your data as a struct, rather than as two individual arrays, and you will automatically solve the problems.

--
Mats

I have never understand how struct works. That is really new to me.

I had an explanation on this but did never really understand the logic of this.
Do you know any example/approach how this could be added to this examplecode...

Well, it's not really my place to write the code for you, but you could have a struct like this:

Code:

---

struct value {
  int action;
  string symbol;
};

---

Then you create a vector of "value", and store a "value" entry for each data-item you have.

--
Mats

I am not sure if I understand.
This declaration with the struct, is this happening before or after you get the values from the file and the vector that I will create to store these values, this must still be 2 vectors since one vector can´t contain both int and string at the same time ?
I am really lost on this one.

The struct declaration shouldn't be in your main function at all; either in a header file, or at the top of the .c file if you're only using a single source file.

A vector must be of only one type, but that type can be user-defined. In this case, we want a vector of type value.

Code:

---

struct value {
  int action;
  string symbol;
};

---

So where in the code should this be if not in the main function or above the int main ()?

Quote:

---

Originally Posted by Coding

Code:

---

struct value {
  int action;
  string symbol;
};

---

So where in the code should this be if not in the main function or above this ?

---

I would recommend between all the lines that say #include and the line that says int main, if you're not using any .h files of your own. So above main (it needs to be there before you try to use any variables of that type).

yes the struct is difficult to learn

I understand.
Does this meen that I can declare a vector that look like this as I first have declared a struct that is named "Value"
inside int main() ?

Code:

---

std::vector<std::vector<Value> > Values(3, std::vector<Value>(10));

---

When I refer to action and symbol later in the code. Can I put these to this same vector then ?
Has these int and string variables been declared as something else, like a Value ?

We've got a tutorial on structures on the main site, if you're interested.

The syntax is not quite right, I think. You're trying to use 3 as size, and std::vector<Value>(10) as the value for the initializer? That initializer might work, but I wouldn't bother. You can just leave it blank; you'll get uninitialized data to start with, but if you plan to read in each element that won't matter. And you only need one vector:

Code:

---

std::vector<Value> Values;

---

is a currently empty vector of things of Value type. As you read things in, you can use push_back to add them to the vector. This way you don't have to know how many things are in your file ahead of time.

You access members of structs with dots: a_Value_variable.action. In your case Values is a vector of Value, so Values[0] would be the first Value item, which means you can do Values[0].action and Values[0].symbol.

Tabstop,

Thats a good explanation, I think I am close to the solution.
I have tried this code out with all the declarations. But the compiler says that &#180;Symbol&#180; : undeclared identifier.
I beleive I have declared it after the # include.
I will also check the tutorials out..

Code:

---

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <sstream>
#include <string> 
#include <vector>
#include <cmath>
#include <algorithm>

struct Value
        {
                int Action;
                std::string Symbol;
        };

using namespace std;
int main ()
{
       
        char Comma;
        int t = 0;
        std::vector<Value> Values (3);


        ofstream Sort1;
 
        Sort1.open ("Sort1.txt");
        ifstream Sort ("Sort.txt");

        while        (    getline(Sort, Symbol, ',')  )                         
        {
                t = (t + 1);                // Count
               
                Sort >> Action;                // Buy
               
                        Values[t] = Symbol;
                        Values[t] = Action;
                       
               
        }

        std::sort(Values.begin(), Values.end());

                for (int Rowsen = 1; Rowsen < (t + 1); Rowsen++)                        //Number of Lines

                {
                        Sort1 <<
                        Values[Rowsen] << ',' <<
                        Values[Rowsen]
                        << "\n";
                }

                return 0;
}

---

Symbol is only defined in the context of a Value struct. Values[t] -- your indexing is off here, by the way, but that's a sidebar -- is a Value hence Values[t].Symbol is defined. Symbol by itself is not.

I beleive I have to check out the tutorials. There is somthing I cant understand with the logic. I think I am near to understand but something is missing...

That means roughly what it says: if you want to initialize Action2 in that manner, then it must be a static constant -- which means that (1) each Value would share the same copy of it[1] and (2) its value could never change.

This isn't what you want, so don't do that. (You don't need to initialize it anyway, since you shouldn't use it until you read in a value from your file.)

[1]I think. That's what would happen in a class, anyway; I don't know whether it happens that way in a struct.

You can't initialize a variable like this:

Code:

---

                int Action2 = 0;

---

You can only define it at that stage. If there were a class definition, you could make a class constructor to fix it. I'm not sure how to fix this without digging into the book.

Todd

Yes I just figured out as I got your answer so I deleted the code just before.
So I have compile success when declaring it like: int Action2
But I only have this If I do this with the line that do the sort for Values:

//std::sort(Values.begin(), Values.end());

So something must be wrong here. The thing is that I will sort for the Action value. Perheps this should be specified in any way.

Code:

---

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <sstream>
#include <string> 
#include <vector>
#include <cmath>
#include <algorithm>

struct Value
        {
                int Action2;
                std::string Symbol2;
        };

using namespace std;
int main ()
{
       
        char Comma;
        int t = 0;
        std::string Symbol;
        int Action = 0;
        std::vector<Value> Values (3);


        ofstream Sort1;
 
        Sort1.open ("Sort1.txt");
        ifstream Sort ("Sort.txt");

        while        (    getline(Sort, Symbol, ',')  )                         
        {
                t = (t + 1);                // Count
               
                Sort >> Action;                // Buy

                        Values[t].Symbol2 = Symbol;
                        Values[t].Action2 = Action;
       
               
        }

                //std::sort(Values.begin(), Values.end());

                for (int Rowsen = 1; Rowsen < (t + 1); Rowsen++)                        //Number of Lines

                {
                        Sort1 <<
                                Values[Rowsen].Symbol2 << ',' <<
                                Values[Rowsen].Action2
                        << "\n";
                }

                return 0;
}

---

The problem is that C++ doesn't know how to sort these new-fangled Value objects, since you haven't told it how. You're going to have to define what < means for Values. Someone will chime in if I'm wrong, but I believe you need to define this function:

Code:

---

bool operator < (const Value& lhs, const Value& rhs) {
// returns true if lhs < rhs, false otherwise
// code goes here
}

---

(Technically you can call it anything you want, but if you call it something else you have to specify that function in your sort call.)
This way the sort algorithm knows whether this guy is less than that one.

Yes that right ofcourse... I will check these functions out and laborate with this and see what I get... Thanks for your help !

I am trying to do a sort so the contents in a .txt file that look like this:
ABC,3
DEF,2

will look like this: (Ascending order for the number) (The sorting is for the numbers(Called Action2 in my code)
DEF,2
ABC,3

I using stucts to manage this but have a problem to understand what I should do with the these lines that is doing the rules for the sort and then sorting it.
I beleive it should be written "Bool operator" and if the x value is less than the y value inside the parathes Bool evaluates TRUE. I think the logics stands for this.

Then it is many things I dont understand, like if the values x and y is exampleletters or should it stand something else here in my case ?
The next line with return is the same, what should be written instead of x.Values ?
For the sort that coming next.
Should it only be written Values.begin() or do I have to refer to Action2 ?

Code:

---

bool operator < (const Value& x, const Value& y)
 {
  return x.Values < y.Values
 };
  std::sort(Values.begin(), Values.end());

---

Code:

---

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <sstream>
#include <string> 
#include <vector>
#include <cmath>
#include <algorithm>

struct Value
        {
                int Action2;
                std::string Symbol2;
        };

using namespace std;
int main ()
{
       
        char Comma;
        int t = 0;
        std::string Symbol;
        int Action = 0;
        std::vector<Value> Values (3);


        ofstream Sort1;
 
        Sort1.open ("Sort1.txt");
        ifstream Sort ("Sort.txt");

        while        (    getline(Sort, Symbol, ',')  )                         
        {
                t = (t + 1);                // Count
               
                Sort >> Action;                // Buy

                        Values[t].Symbol2 = Symbol;
                        Values[t].Action2 = Action;
       
               
        }

                bool operator < (const Value& x, const Value& y)
                  {
                        return x.Values < y.Values
                  };
                        std::sort(Values.begin(), Values.end());

                for (int Rowsen = 1; Rowsen < (t + 1); Rowsen++)                        //Number of Lines

                {
                        Sort1 <<
                                Values[Rowsen].Symbol2 << ',' <<
                                Values[Rowsen].Action2
                        << "\n";
                }

                return 0;
}

---

And why do you think x.Values means anything? x is a Value -- your function declaration says so! -- so x contains a Symbol2 and an Action2. Same with y.

And of course you can call your parameters of your functions anything you like, provided they aren't keywords like if, or macros. I like to use lhs and rhs, but no one's going to complain about x and y.

Okay, so if x and y contains the Action2 and Symbol2 it makes a little bit more sense to me.

So far that I can manage right now, I think I have to specify what value in the x and y values that is interesting for sorting.. In this case Action2. So I write: x.Action2 < y.Action2
I dont know if this is correct:

Code:

---

bool operator < (const Value& x, const Value& y)

 {
  return x.Action2 < y.Action2;
 };
    std::sort(Values.begin(), Values.end());

---

The compiler says that:
'operator <' : local function definitions are illegal
a '{' which has not yet been matched

Don't define functions within other functions.

Even if I change this line to this. Still there is something that isn&#180;t correct. The Compiler isn&#180;t happy.

Code:

---

{
return x.Action2 < y.Action2
};

---

You are implementing the function "operator<" inside another function (main) in the code you posted above. You need to move this function out of there and above main (or below, if you declare a prototype above).

--
Mats

Thank You matsp... This was the mainproblem I had. I didn&#180;t know that this function had to be ouside the main. So now it is working. Couldn&#180;t understand what was wrong... Thanks...

In standard C or C++ (rather than extensions such as gcc), you can NEVER define a function inside another function. Some other languages, such as Pascal, allows you to define a function inside another function - but C and C++ doesn't.

You can define a class member function inside a class, that is just about the only time you can declare a function inside of curly brackets.

--
Mats

Yes okay I see. That was what I wondered also. I knew that Pascal could do it so I was a bit confused about it. Now I have a lot to experiment on :-)