c++ json lib: nlohmann::json

nlohmann::json is a popluar json lib.

code at: https://github.com/nlohmann/json

document at: https://nlohmann.github.io/json/doxygen/index.html

sample code:

There are several ways to for value access :

value access

• get – get a value
• get_ptr – get a value pointer
• get_ref – get a value reference
• get_binary – get a binary value
• operator ValueType – get a value (implicit conversion)
• value – get a value from an object and return default value if key is not present

in addtion,  there are: jsonobj.at(“key”),   jsonobj[“key”] etc  . quite confusing if you r newbie,

Here is the document:

.value():

Unlike at(const typename object_t::key_type&), this function does not throw if the given key key was not found.

Unlike operator[](const typename object_t::key_type& key), this function does not implicitly add an element to the position defined by key. This function is furthermore also applicable to const objects.