How do I find an element position in std::vector?

Question

I need to find an element position in an std::vector to use it for referencing an element in another vector:

int find( const vector& whe         


        

Answer 1

If a vector has N elements, there are N+1 possible answers for find. std::find and std::find_if return an iterator to the found element OR end() if no element is found. To change the code as little as possible, your find function should return the equivalent position:

size_t find( const vector& where, int searchParameter )
{
   for( size_t i = 0; i < where.size(); i++ ) {
       if( conditionMet( where[i], searchParameter ) ) {
           return i;
       }
    }
    return where.size();
}
// caller:
const int position = find( firstVector, parameter );
if( position != secondVector.size() ) {
    doAction( secondVector[position] );
}

I would still use std::find_if, though.