Given the following usage of auto
:
std::vector<int> v;
for (auto i = 0; i < v.size(); ++i) {
...
}
It would be ideal for C++ to deduce i
as std::vector<int>::size_type
, but if it only looks at the initializer for i
, it would see an integer. What is the deduced type of i
in this case? Is this appropriate usage of auto
?
Use decltype
instead of auto
to declare i
.
for( decltype(v.size()) i = 0; i < v.size(); ++i ) {
// ...
}
Even better, use iterators to iterate over the vector as @MarkB's answer shows.