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nlohmann
74 lines
1.8 KiB
Markdown
74 lines
1.8 KiB
Markdown
# nlohmann::basic_json::array_t
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```
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using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
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```
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The type used to store JSON arrays.
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[RFC 8259](https://tools.ietf.org/html/rfc8259) describes JSON arrays as follows:
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> An array is an ordered sequence of zero or more values.
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To store objects in C++, a type is defined by the template parameters explained below.
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## Template parameters
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`ArrayType` : container type to store arrays (e.g., `std::vector` or `std::list`)
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`AllocatorType` : the allocator to use for objects (e.g., `std::allocator`)
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## Notes
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#### Default type
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With the default values for `ArrayType` (`std::vector`) and `AllocatorType` (`std::allocator`), the default value for `array_t` is:
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```
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std::vector<
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basic_json, // value_type
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std::allocator<basic_json> // allocator_type
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>
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```
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#### Limits
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[RFC 8259](https://tools.ietf.org/html/rfc8259) specifies:
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> An implementation may set limits on the maximum depth of nesting.
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In this class, the array's limit of nesting is not explicitly constrained. However, a maximum depth of nesting may be introduced by the compiler or runtime environment. A theoretical limit can be queried by calling the [`max_size`](https://json.nlohmann.me/api/basic_json/max_size/index.md) function of a JSON array.
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#### Storage
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Arrays are stored as pointers in a `basic_json` type. That is, for any access to array values, a pointer of type `array_t*` must be dereferenced.
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## Examples
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Example
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The following code shows that `array_t` is by default, a typedef to `std::vector<nlohmann::json>`.
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```
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#include <iostream>
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#include <iomanip>
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#include <nlohmann/json.hpp>
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using json = nlohmann::json;
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int main()
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{
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std::cout << std::boolalpha << std::is_same<std::vector<json>, json::array_t>::value << std::endl;
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}
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```
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Output:
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```
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true
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```
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## Version history
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- Added in version 1.0.0.
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