# out_of_range - JSON for Modern C++
Author: Niels Lohmann

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# nlohmann::basic_json::out_of_range

    class out_of_range : public exception;

This exception is thrown in case a library function is called on an input parameter that exceeds the expected range, for instance, in the case of array indices or nonexisting object keys.

Exceptions have ids 4xx (see list of out-of-range errors).

    classDiagram
      direction LR

        class std_exception ["std::exception"] {
            <<interface>>
        }

        class json_exception ["basic_json::exception"] {
            +const int id
            +const char* what() const
        }

        class json_parse_error ["basic_json::parse_error"] {
            +const std::size_t byte
        }

        class json_invalid_iterator ["basic_json::invalid_iterator"]
        class json_type_error ["basic_json::type_error"]
        class json_out_of_range ["basic_json::out_of_range"]
        class json_other_error ["basic_json::other_error"]

        std_exception <|-- json_exception
        json_exception <|-- json_parse_error
        json_exception <|-- json_invalid_iterator
        json_exception <|-- json_type_error
        json_exception <|-- json_out_of_range
        json_exception <|-- json_other_error

        style json_out_of_range fill:#CCCCFF

## Member functions

- what - returns explanatory string

## Member variables

- id - the id of the exception

## Examples

Example

The following code shows how a `out_of_range` exception can be caught.

    #include <iostream>
    #include <nlohmann/json.hpp>

    using json = nlohmann::json;

    int main()
    {
        try
        {
            // calling at() for an invalid index
            json j = {1, 2, 3, 4};
            j.at(4) = 10;
        }
        catch (const json::out_of_range& e)
        {
            // output exception information
            std::cout << "message: " << e.what() << '\n'
                      << "exception id: " << e.id << std::endl;
        }
    }

Output:

    message: [json.exception.out_of_range.401] array index 4 is out of range
    exception id: 401

## See also

- List of out-of-range errors
- `parse_error` for exceptions indicating a parse error
- `invalid_iterator` for exceptions indicating errors with iterators
- `type_error` for exceptions indicating executing a member function with a wrong type
- `other_error` for exceptions indicating other library errors

## Version history

- Since version 3.0.0.

November 12, 2025