Simpler way to set multiple array slots to one value

Question

I\'m coding in C++, and I have the following code:

int array[30];
array[9] = 1;
array[5] = 1;
array[14] = 1;

array[8] = 2;
array[15] = 2;
array[23] = 2;
array[1         


        

Answer 1

Compilers which still doesn't support variadic template argument and universal initialization list, it can be a pain to realize, that some of the posted solution will not work

As it seems, OP only intends to work with arrays of numbers, valarray with variable arguments can actually solve this problem quite easily.

#include      
#include 
#include 
#include 
#include 
template 
std::valarray  selection( ... )
{
    va_list arguments; 
    std::valarray sel(size);   
    //Skip the first element
    va_start ( arguments, size );
    va_arg ( arguments, int );
    for(auto &elem : sel)
        elem = va_arg ( arguments, int );
    va_end ( arguments );
    return sel;

}
int main ()
{
    //Create an array of 30 integers
    std::valarray array(30);
    //The first argument is the count of indexes
    //followed by the indexes of the array to initialize
    array[selection<3>(9,5,14)] = 1;
    array[selection<4>(8,15,13, 12)] = 2;
    std::copy(std::begin(array), std::end(array),
              std::ostream_iterator(std::cout, " "));
    return 0;
}