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>
Returns a const reference to the element at with specified JSON pointer ptr, with bounds checking.
- Parameters
-
[in] | ptr | JSON pointer to the desired element |
- Returns
- reference to the element pointed to by ptr
- Exceptions
-
parse_error.106 | if an array index in the passed JSON pointer ptr begins with '0'. See example below. |
parse_error.109 | if an array index in the passed JSON pointer ptr is not a number. See example below. |
out_of_range.401 | if an array index in the passed JSON pointer ptr is out of range. See example below. |
out_of_range.402 | if the array index '-' is used in the passed JSON pointer ptr. As at provides checked access (and no elements are implicitly inserted), the index '-' is always invalid. See example below. |
out_of_range.403 | if the JSON pointer describes a key of an object which cannot be found. See example below. |
out_of_range.404 | if the JSON pointer ptr can not be resolved. See example below. |
- Exception safety^^ Strong guarantee: if an exception is thrown, there are no
- changes in the JSON value.
- Complexity^^ Constant.
- Since
- version 2.0.0
- Example^^ The behavior is shown in the example. ^^ at_json_pointer_const.cpp
- Output (play with this example online):^^
1
"foo"
[1,2]
2
[json.exception.parse_error.109] parse error: array index 'one' is not a number
[json.exception.out_of_range.401] array index 4 is out of range
[json.exception.out_of_range.402] array index '-' (2) is out of range
[json.exception.out_of_range.403] key 'foo' not found
[json.exception.out_of_range.404] unresolved reference token 'foo'
^^ The example code above can be translated withg++ -std=c++11 -Isingle_include doc/examples/at_json_pointer_const.cpp -o at_json_pointer_const
Definition at line 19673 of file json.hpp.