json/doc/examples/contains_json_pointer.cpp

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#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// create a JSON value
json j =
{
{"number", 1}, {"string", "foo"}, {"array", {1, 2}}
};
std::cout << std::boolalpha
<< j.contains("/number"_json_pointer) << '\n'
<< j.contains("/string"_json_pointer) << '\n'
<< j.contains("/array"_json_pointer) << '\n'
<< j.contains("/array/1"_json_pointer) << '\n'
<< j.contains("/array/-"_json_pointer) << '\n'
<< j.contains("/array/4"_json_pointer) << '\n'
<< j.contains("/baz"_json_pointer) << std::endl;
try
{
// try to use an array index with leading '0'
j.contains("/array/01"_json_pointer);
}
catch (json::parse_error& e)
{
std::cout << e.what() << '\n';
}
try
{
// try to use an array index that is not a number
j.contains("/array/one"_json_pointer);
}
catch (json::parse_error& e)
{
std::cout << e.what() << '\n';
}
}