basic_json::find¶
template<typename KeyT>
iterator find(KeyT&& key);
template<typename KeyT>
const_iterator find(KeyT&& key) const
Finds an element in a JSON object with key equivalent to key
. If the element is not found or the JSON value is not an object, end()
is returned.
Template parameters¶
KeyT
- A type for an object key.
Parameters¶
key
(in)- key value of the element to search for.
Return value¶
Iterator to an element with key equivalent to key
. If no such element is found or the JSON value is not an object, past-the-end (see end()
) iterator is returned.
Exception safety¶
Strong exception safety: if an exception occurs, the original value stays intact.
Complexity¶
Logarithmic in the size of the JSON object.
Notes¶
This method always returns end()
when executed on a JSON type that is not an object.
Example¶
Example
The example shows how find()
is used.
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// create a JSON object
json j_object = {{"one", 1}, {"two", 2}};
// call find
auto it_two = j_object.find("two");
auto it_three = j_object.find("three");
// print values
std::cout << std::boolalpha;
std::cout << "\"two\" was found: " << (it_two != j_object.end()) << '\n';
std::cout << "value at key \"two\": " << *it_two << '\n';
std::cout << "\"three\" was found: " << (it_three != j_object.end()) << '\n';
}
Output:
"two" was found: true
value at key "two": 2
"three" was found: false
Version history¶
- Added in version 1.0.0.