JSON for Modern C++  1.1.0
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 = int64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator>
template<class InteratorType , typename std::enable_if< std::is_same< InteratorType, typename basic_json_t::iterator >::value or std::is_same< InteratorType, typename basic_json_t::const_iterator >::value , int >::type = 0>
InteratorType nlohmann::basic_json::erase ( InteratorType  first,
InteratorType  last 
)
inline

Removes the element specified by the range [first; last). Invalidates iterators and references at or after the point of the erase, including the end() iterator. The iterator first does not need to be dereferenceable if first == last: erasing an empty range is a no-op.

If called on a primitive type other than null, the resulting JSON value will be null.

Parameters
[in]firstiterator to the beginning of the range to remove
[in]lastiterator past the end of the range to remove
Returns
Iterator following the last removed element. If the iterator second refers to the last element, the end() iterator is returned.
Template Parameters
InteratorTypean iterator or const_iterator
Exceptions
std::domain_errorif called on a null value; example: "cannot use erase() with null"
std::domain_errorif called on iterators which does not belong to the current JSON value; example: "iterators do not fit current value"
std::out_of_rangeif called on a primitive type with invalid iterators (i.e., if first != begin() and last != end()); example: "iterators out of range"
Complexity
The complexity depends on the type:
  • objects: log(size()) + std::distance(first, last)
  • arrays: linear in the distance between first and last, plus linear in the distance between last and end of the container
  • strings: linear in the length of the string
  • other types: constant
Example
The example shows the result of erase for different JSON types.
1 #include <json.hpp>
2 
3 using namespace nlohmann;
4 
5 int main()
6 {
7  // create JSON values
8  json j_boolean = true;
9  json j_number_integer = 17;
10  json j_number_float = 23.42;
11  json j_object = {{"one", 1}, {"two", 2}};
12  json j_array = {1, 2, 4, 8, 16};
13  json j_string = "Hello, world";
14 
15  // call erase
16  j_boolean.erase(j_boolean.begin(), j_boolean.end());
17  j_number_integer.erase(j_number_integer.begin(), j_number_integer.end());
18  j_number_float.erase(j_number_float.begin(), j_number_float.end());
19  j_object.erase(j_object.find("two"), j_object.end());
20  j_array.erase(j_array.begin() + 1, j_array.begin() + 3);
21  j_string.erase(j_string.begin(), j_string.end());
22 
23  // print values
24  std::cout << j_boolean << '\n';
25  std::cout << j_number_integer << '\n';
26  std::cout << j_number_float << '\n';
27  std::cout << j_object << '\n';
28  std::cout << j_array << '\n';
29  std::cout << j_string << '\n';
30 }
a class to store JSON values
Definition: json.hpp:191
iterator end()
returns an iterator to one past the last element
Definition: json.hpp:3833
iterator begin()
returns an iterator to the first element
Definition: json.hpp:3774
iterator find(typename object_t::key_type key)
find an element in a JSON object
Definition: json.hpp:3691
namespace for Niels Lohmann
Definition: json.hpp:88
InteratorType erase(InteratorType pos)
remove element given an iterator
Definition: json.hpp:3429
Output (play with this example online):
null
null
null
{"one":1}
[1,8,16]
null
The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/erase__IteratorType_IteratorType.cpp -o erase__IteratorType_IteratorType 
See also
erase(InteratorType) – removes the element at a given position
erase(const typename object_t::key_type&) – removes the element from an object at the given key
erase(const size_type) – removes the element from an array at the given index
Since
version 1.0.0

Definition at line 3534 of file json.hpp.