Question

Say I have an object containing a value. I wish to get the index of object with a particular value from a list of objects. I use the below code to do it,

int MyClass::getIndex(list& somelist, int requiredValue)
{

    for( i=0; i != somelist.count(); ++i)
    {

        if(somelist.at(i)->value() == requiredValue)
            return i;
        else
            continue;
    }

return -1;
}

How to avoid the “doesn’t return a value on all code paths” warning without using an iterator?

Answer 1

You must return T from the function in any case. If the value possibly does not exists in the list you have options:

1. return default value (nullptr for pointer for example, -1 for integer possibly)
2. use boost::optional<T>

3. return end iterator:

   std::list<int>::iterator find_something(std::list<int> &my_list)
   {
        for (auto it = my_list.begin(); it != my_list.end(); ++it)
        { 
            if (cond)
            {
                return it;
            }
        }
   
        return my_list.end();
   }
   

Also

If you just want to find the iterator to some value, use std::find:

auto it = std::find(my_list.begin(), my_list.end(), my_value);

Finally

Don’t use list if you need access by index. Use vector in that case