Array in C++

Question

hi guys, i have to do a function which returns an array of 0 and 1, which order depends on the parameter passed to the function;
for example using js i would have done something like this:

function f(n){
var stmap;
switch(n){
case 0: stmap=[1,1,1,1,1,1,0]; break;
case 1: stmap=[0,1,1,0,0,0,0]; break;
...ecc
}
return stmap;
}

using C++, i do:
case0:
stmap[0]=1;
stmap[1]=1;
..ecc
is there a faster method?

Answer 1

You can use an initializer_list for this.
http://en.cppreference.com/w/cpp/utility/initializer_list
like: int arr[4] = {0,1,1,0};

If for some reason you can't initialize it immediatly after declaring you can make your own function.

template<typename T>
void copyPattern( T* arr, const std::initializer_list<T>& il )
{
std::size_t index = 0;
for( const auto& i : il )
arr[index++] = i;
}

then you can call it like:
int arr[10];
// Skipping init

copyPattern( arr, {1,1,0,1} );
Fills in arr[0] through arr[3] with the pattern.

copyPattern( arr + 5, {1,1,0,1} );
Fills in arr[5] through arr[8] with the pattern.

Note that the function does not do any out-of-bounds checking.

Also note that C++ cannot return arrays from functions.
It can return pointers that point to the start of an array though but then you'll have to play with new/delete.

Might want to look at std::vectors.
http://en.cppreference.com/w/cpp/container/vector

Answer 2

thank you @Dennis
i have never seen this code, i don't understand it at all, i have to deepen it a bit more, but it seems good ;)