JSON for Modern C++  3.5.0

◆ back() [1/2]

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>
reference nlohmann::basic_json::back ( )
inline

Returns a reference to the last element in the container. For a JSON container c, the expression c.back() is equivalent to

auto tmp = c.end();
--tmp;
return *tmp;
Returns
In case of a structured type (array or object), a reference to the last element is returned. In case of number, string, or boolean values, a reference to the value is returned.
Complexity^^ Constant.
Precondition
The JSON value must not be null (would throw std::out_of_range) or an empty array or object (undefined behavior, guarded by assertions).
Postcondition
The JSON value remains unchanged.
Exceptions
invalid_iterator.214when called on a null value. See example below.
Example^^ The following code shows an example for back(). ^^ back.cpp
Output (play with this example online):^^
true
17
23.42
2
16
"Hello, world"
[json.exception.invalid_iterator.214] cannot get value
^^ The example code above can be translated with
g++ -std=c++11 -Isingle_include doc/examples/back.cpp -o back 
See also
front() – access the first element
Since
version 1.0.0

Definition at line 15950 of file json.hpp.