performance-inefficient-vector-operation¶
Finds possible inefficient std::vector operations (e.g. push_back,
emplace_back) that may cause unnecessary memory reallocations.
Currently, the check only detects following kinds of loops with a single statement body:
- Counter-based for loops start with 0:
std::vector<int> v;
for (int i = 0; i < n; ++i) {
v.push_back(n);
// This will trigger the warning since the push_back may cause multiple
// memory reallocations in v. This can be avoid by inserting a 'reserve(n)'
// statement before the for statement.
}
- For-range loops like
for (range-declaration : range_expression), the type ofrange_expressioncan bestd::vector,std::array,std::deque,std::set,std::unordered_set,std::map,std::unordered_set:
std::vector<int> data;
std::vector<int> v;
for (auto element : data) {
v.push_back(element);
// This will trigger the warning since the 'push_back' may cause multiple
// memory reallocations in v. This can be avoid by inserting a
// 'reserve(data.size())' statement before the for statement.
}