std::vector construction

[mlt]

Is there someway to create a std::vector from a sequence of numbers? On this
page:

http://www.cppreference.com/wiki/stl/vector/vector_constructors

there are 4 different constructors, but none of them supports something
like:

std::vector<int> v = {1,2,3};

Its only possible to do it like:

std::vector<int> v;

v.push_back(1,2,3);

 

[Alf P. Steinbach]

* mlt:

Is there someway to create a std::vector from a sequence of numbers? On this
page:

http://www.cppreference.com/wiki/stl/vector/vector_constructors

there are 4 different constructors, but none of them supports something
like:

std::vector<int> v = {1,2,3};

Its only possible to do it like:

std::vector<int> v;

v.push_back(1,2,3);

The usual is to declare the static data as static data, e.g.

static int data[] = {1, 2, 3};
static size_t const n = sizeof( data )/sizeof( *data );

std:vector<int> v( data, data + n );

Cheers & hth.,

- Alf

 

[Alf P. Steinbach]

* Alf P. Steinbach:

* mlt:

Is there someway to create a std::vector from a sequence of numbers?
On this page:

http://www.cppreference.com/wiki/stl/vector/vector_constructors

there are 4 different constructors, but none of them supports
something like:

std::vector<int> v = {1,2,3};

Its only possible to do it like:

std::vector<int> v;

v.push_back(1,2,3);

The usual is to declare the static data as static data, e.g.

static int data[] = {1, 2, 3};
static size_t const n = sizeof( data )/sizeof( *data );

std:vector<int> v( data, data + n );

Add a 'const' in the 'data' declaration.


Cheers & sorry for typo,

- Alf, on Friday 13th, no coffee

 

[ZikO]

Is there someway to create a std::vector from a sequence of numbers? On this
page:

http://www.cppreference.com/wiki/stl/vector/vector_constructors

there are 4 different constructors, but none of them supports something
like:

std::vector<int> v = {1,2,3};

Its only possible to do it like:

std::vector<int> v;

v.push_back(1,2,3);

AFAIK you can't do that by constructor. You could however use generate()
or generate_n() algorythm in <algorithm> head file and fill empty vector
with values generated by Generator. You however, need, generator


Something like this

#include <iostream>
#include <algorithm>
#include <vector>
#include <iterator>

using namespace std;

class Gen { // generator
private:
int value;
int step;
public:
Gen(int bb = 0, int ss = 1) : value(bb), step(ss) {}
int operator()() {
int old = value;
value += step;
return old;
}
};

int main() {
vector<int> v1;
generate_n(back_inserter(v1), 50, Gen(1,1));

vector<int> v2(50);
generate(v2.begin(), v2.end(), Gen(0,5));

for(int i=0; i<v1.size(); i++) {
cout << v1 << " ";
}
cout << endl;

for(int i=0; i<v2.size(); i++) {
cout << v2 << " ";
}
cout << endl;
}

Hopefuly it helped.

 

[Boris Schaeling]

Is there someway to create a std::vector from a sequence of numbers? On
this
page:

http://www.cppreference.com/wiki/stl/vector/vector_constructors

there are 4 different constructors, but none of them supports something
like:

std::vector<int> v = {1,2,3};

If you use Boost I think you can initialize the container with:

std::vector<int> v = boost::assign::list_of(1)(2)(3);

Boris

 

[James Kanze]

Is there someway to create a std::vector from a sequence of
numbers? On this page:

there are 4 different constructors, but none of them supports
something like:

std::vector<int> v = {1,2,3};

Its only possible to do it like:

std::vector<int> v;

v.push_back(1,2,3);

There are several solutions. As Alf has pointed out, you can
always copy a staticly initialized C-style array (although it's
more idiomatic---and less error prone---to use template
functions to get the start and end addresses). For specific
instances where the sequence can be calculated, however, I'd
look into Boosts iterator adapters (to be used with the same
constructor---the template one with two iterators).