I recently asked this question about converting an array of objects into a vector of structs. I want to do the same thing, but rather vectors I want an array. For example
[
{
"Name": "Test",
"Val": "TestVal"
},
{
"Name": "Test2",
"Val": "TestVal2"
}
]
And want an array of of these structs:
struct Test {
string Name;
string Val;
};
How can this be possible? I am new to c++ so if I am doing anything wrong please say so.
The easiest thing to do is use, wherever you can, std::array instead of C arrays. std::array is a C++ analogue to plain arrays that adds all the nice stuff from std::vector like size() and iterators. You can also return them from functions, unlike C arrays.
nlohmann also supports it automatically:
auto parsed = json.get<std::array<Test, 2>>();
Not sure about the library's support for plain ol' C arrays. But you can write a helper function with a little template magic:
template <typename T, size_t N>
void from_json(const nlohmann::json& j, T (&t)[N]) {
if (j.size() != N) {
throw std::runtime_error("JSON array size is different than expected");
}
size_t index = 0;
for (auto& item : j) {
from_json(item, t[index++]);
}
}
usage:
Test my_array[N];
from_json(json, my_array);
