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55 lines
1.3 KiB
Markdown
55 lines
1.3 KiB
Markdown
# nlohmann::basic_json::boolean_t
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```
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using boolean_t = BooleanType;
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```
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The type used to store JSON booleans.
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[RFC 8259](https://tools.ietf.org/html/rfc8259) implicitly describes a boolean as a type which differentiates the two literals `true` and `false`.
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To store boolean values in C++, a type is defined by the template parameter `BooleanType` which chooses the type to use.
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## Template parameters
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`BooleanType` : the type to store booleans. As it is stored directly inside a `basic_json` value (in a union), it must be a trivially default-constructible, trivially copyable, and trivially destructible type that is convertible to and from `bool`. See [Template Parameter Requirements](https://json.nlohmann.me/features/types/template_parameters/#booleantype).
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## Notes
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#### Default type
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With the default values for `BooleanType` (`bool`), the default value for `boolean_t` is `bool`.
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#### Storage
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Boolean values are stored directly inside a `basic_json` type.
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## Examples
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Example
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The following code shows that `boolean_t` is by default, a typedef to `bool`.
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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<bool, json::boolean_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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