Thread: What is the C++ equivalent for Python...

Hi everyone

In Python, I know how the following works:

Code:

>>> SET = []
>>> SET.append(1)
>>> print SET
[1]

An empty set is first defined.
The integer 1 is added/appended to the set.
The set is printed, having one new element instead of being empty.

How would I go about doing this in C++?
Would it look something like this?

Code:

#include <iostream>
#include <set>
using namespace std;

int main()
{
    set<int> SET;
    SET.insert(1)
    cout << SET << endl;
}

I tried doing that but I got an error saying
no match for 'operator<<' in 'std::cout << SET'
I am using DevC++ 4.9.9.2 and Python 2.7

Thank you all in advance

You'll have to walk the set and print each member.

How can I append new elements to the set as shown in the Python example?
Is there a way to declare an empty set and add new members to it?

Thanks guys.

I'm still quite confused >_<

I went ahead and looked up std::list at
Cprogramming.com - STL Tutorial - List Container

I copied and pasted the last portion:

Code:

std::list<int> int_list;
int_list.push_back(1);
int_list.push_back(1);
int_list.push_back(8);
int_list.push_back(9);
int_list.push_back(7);
int_list.push_back(8);
int_list.push_back(2);
int_list.push_back(3);
int_list.push_back(3);
int_list.sort();
int_list.unique();

for(std::list<int>::iterator list_iter = int_list.begin(); 
    list_iter != int_list.end(); list_iter++)
{
    std::cout<<list_iter<<endl;
}

I have the same error as before (which is strange since I thought this would be a working model).
I don't know all the terms being used in your answers.

If it doesn't bother you guys, could you post the simplest sample code that would reflect the behaviour of defining a list/set/array and inserting elements to it?
I understand that those datatypes slightly differ, but I'll look into those right now.
I'm taking notes as I go, but things are a bit confusing still.

Thanks for all your help. Much appreciated!

Originally Posted by CPlus

Thanks guys.

I'm still quite confused >_<

I went ahead and looked up std::list at
Cprogramming.com - STL Tutorial - List Container

I copied and pasted the last portion:

Code:

std::list<int> int_list;
int_list.push_back(1);
int_list.push_back(1);
int_list.push_back(8);
int_list.push_back(9);
int_list.push_back(7);
int_list.push_back(8);
int_list.push_back(2);
int_list.push_back(3);
int_list.push_back(3);
int_list.sort();
int_list.unique();

for(std::list<int>::iterator list_iter = int_list.begin(); 
    list_iter != int_list.end(); list_iter++)
{
    std::cout<<list_iter<<endl;
}

I have the same error as before (which is strange since I thought this would be a working model).
I don't know all the terms being used in your answers.

If it doesn't bother you guys, could you post the simplest sample code that would reflect the behaviour of defining a list/set/array and inserting elements to it?
I understand that those datatypes slightly differ, but I'll look into those right now.
I'm taking notes as I go, but things are a bit confusing still.

Thanks for all your help. Much appreciated!

You need this:

Code:

std::cout<<*list_iter<<endl;

list_iter itself is not an object, it merely points to where the object is. You have to follow that pointer to find the object.

Thanks! That worked.

If int_list is the list, is there any way I can cout the Nth element in it?
For example, if int_list was 1,1,2,6,24,120
then
int_list[0] would be 1,
int_list[1] would be 1,
int_list[2] would be 2,
int_list[3] would be 6,
int_list[4] would be 24,
int_list[5] would be 120,

Thanks in advance
You guys are a lot of help.

You don't have random access for a list. But you can do the walking algorithm that you just did, but with a counter to tell you when to stop.

It works

The code I used was:

Code:

int main()
{
    vector<int> VECTOR;
    VECTOR.push_back(1);
    VECTOR.push_back(1);
    VECTOR.push_back(2);
    VECTOR.push_back(6);
    VECTOR.push_back(24);    
    cout << VECTOR[4] << endl;
}

Which outputted 24.


I have another question that is related to all of this.
In Python, a user can input a list, such as:

Code:

LIST = input("Input your list here: ")
LIST.append(1)
print LIST

What this does is ask the user to input a list called LIST.
Afterward, LIST has the number 1 appended to it.
If the user writes [0,1,2,3,4,5] as their input LIST, the
script outputs [0,1,2,3,4,5,1]

Would the C++ equivalent look something like this?

Code:

int main()
{
    // VECTOR defined here
    vector<int> VECTOR;

    // User inputs into VECTOR
    std::cin>>VECTOR;

    // Adds "1" into VECTOR
    VECTOR.push_back(1);

    // couts from 0 to Vector size
    for (i==0;i<(VECTOR.size());i++)
    {
        cout << VECTOR[i] << endl;
    }
}

Thanks for all your help