Iterating over a QMap with for

Question

I\'ve a QMap object and I am trying to write its content to a file.

QMap extensions;
//.. 

for(auto e : extensions)
{
  fou         


        

Answer 1

Ivan Čukić of KDAB has a blog post that explains how to iterate over a QMap with C++17 structured bindings without copying the container:

template 
class asKeyValueRange
{
public:
    asKeyValueRange(T &data) : m_data{data} {}

    auto begin() { return m_data.keyValueBegin(); }

    auto end() { return m_data.keyValueEnd(); }

private:
    T &m_data;
};

...

QMap extensions;

for (auto [key, value]: asKeyValueRange(extensions))
{
    fout << key << ',' << value << '\n';
}