how to decleare a 1D double array - c++

Question

Data input from the keyboard.The length of array maybe very long.
I want to finish inputing when press ENTER twice.
the numbers separated by space, tab or ",". how to detect the length n?
I have tried like this:
#include<iostream>
#include<string>
#include<sstream>
using namespace std;
void main()
{
bool flag=true;
unsigned n=0,i;
double x;
string line,str;
istringstream iss;
cout<<"input your numbers."<<endl;
count<<"Press the Enter key twice finish data inputting."<<endl;
while(flag)
{
getline(cin,line);
str+=line+' ';
if(line.empty())
flag=false;
}
// get the length n
iss.str(str);
while(iss>>x)
{
n++;
}
double *v=new double[n];
iss.seekg(0);
for(i=0;i<n;i++)
iss>>v[i];
for(i=0;i<n;i++)
{
cout<<v[i];
if(i<n-1)
cout<<' ';
}
cout<<endl;
delete []v;
}
I am a novice. Help me, Please!

Answer 1

Try this After taking the input in variable line do this:
#include<iostream>
#include<string>
#include<sstring>
using namespace std;
void main()
{
bool flag=true;
unsigned n,i=0;
double x;
string line,str;
istringstream iss;
cout<<"input your "
getline(cin,line);
int c=0;
char * pch;
pch = strtok (line," ,");// this will work for space and comma but you can add your own specifiers
while (pch != NULL)
{
printf ("%s\n",pch);
pch = strtok (NULL, " ,");
c++;
}
return(c);// will give the length of arry.
}

Answer 2

Man to declare 1D array
the syntax is
void main()
{
int array[5];
//to initalize;
for(int i=0;i<5;i++)
{
array[i]=i;
}
for(int i=0;i<5;i++)
{
cout<<array[i]<<" ";
}
// and to declare dynamically
int * array=new int[5];
}

Answer 3

I have solved this problem.
#include<iostream>
#include<string>
#include<sstream>
using namespace std;
void main()
{
bool flag=true;
unsigned n=0,i;
double x;
string line,str;
istringstream iss;
cout<<"input your numbers."<<endl;
cout<<"Press the Enter key twice finish data inputting."<<endl;
//Brecause data may come from clipboard and have multi line.
while(flag)
{
getline(cin,line);
str+=line+'\n';
// vc++ 6.0 have a bug in include file: STRING. You shoud fix it.
//Or you shoud press ENTER more than twice to terminate inputing.
//Replace I.rdbuf()->snextc(); to _I.rdbuf()->sbumpc();
if(line.empty())
flag=false;
}
// get the length n
iss.str(str);
while(iss>>x)
{
n++;
}
double *v=new double[n];
iss.clear();// very important.
// initialize v[n]
iss.str(str);
for(i=0;i<n;i++)
iss>>v[i];
// output v
for(i=0;i<n;i++)
{
cout<<v[i];
if(i<n-1)
cout<<' ';
}
cout<<endl;
delete []v;
}