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1.2 KiB
1.2 KiB
nlohmann::basic_json::empty
bool empty() const noexcept;
Checks if the container has no elements; that is, whether begin() == end()
.
Parameters
(none)
Return value
true
if the container is empty, false
otherwise. Note that the JSON types string, number, and boolean are never empty, null values are always empty.
Exceptions
noexcept
specification: noexcept
.
Complexity
Constant (assuming types ObjectType
and ArrayType
satisfy the Container concept).
Example
The following code uses empty to check if a json
container contains any elements:
#include <json.hpp>
#include <iostream>
int main()
{
nlohman::json numbers;
std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n';
numbers.push_back(42);
numbers.push_back(13317);
std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n';
}
Output
Initially, numbers.empty(): 1
After adding elements, numbers.empty(): 0
Requirements
The empty
member function is part of the Container requirement.
See also
size()