template<template< typename U, typename V, typename... Args > class ObjectType = std::map, template< typename U, typename... Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = std::int64_t, class NumberUnsignedType = std::uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator, template< typename T, typename SFINAE=void > class JSONSerializer = adl_serializer, class BinaryType = std::vector<std::uint8_t>>
Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. The function does not change the JSON value; no null
values are created. In particular, the special value -
yields an exception.
- Parameters
-
[in] | ptr | JSON pointer to the desired element |
- Returns
- const reference to the element pointed to by ptr
- Complexity
- Constant.
- Exceptions
-
parse_error.106 | if an array index begins with '0' |
parse_error.109 | if an array index was not a number |
out_of_range.402 | if the array index '-' is used |
out_of_range.404 | if the JSON pointer can not be resolved |
- Example
- The behavior is shown in the example.
2#include <nlohmann/json.hpp>
11 {
"number", 1}, {
"string",
"foo"}, {
"array", {1, 2}}
17 std::cout << j[
"/number"_json_pointer] <<
'\n';
19 std::cout << j[
"/string"_json_pointer] <<
'\n';
21 std::cout << j[
"/array"_json_pointer] <<
'\n';
23 std::cout << j[
"/array/1"_json_pointer] <<
'\n';
basic_json<> json
default JSON class
Output (play with this example online): 1
"foo"
[1,2]
2
The example code above can be translated with g++ -std=c++11 -Isingle_include doc/examples/operatorjson_pointer_const.cpp -o operatorjson_pointer_const
- Since
- version 2.0.0
Definition at line 25727 of file json.hpp.