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nlohmann
107 lines
3.2 KiB
Markdown
107 lines
3.2 KiB
Markdown
# nlohmann::basic_json::parse_error
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```
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class parse_error : public exception;
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```
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The library throws this exception when a parse error occurs. Parse errors can occur during the deserialization of JSON text, BSON, CBOR, MessagePack, UBJSON, as well as when using JSON Patch.
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Member `byte` holds the byte index of the last read character in the input file (see note below).
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Exceptions have ids 1xx (see [list of parse errors](https://json.nlohmann.me/home/exceptions/#parse-errors)).
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```
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classDiagram
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direction LR
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class std_exception ["std::exception"] {
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<<interface>>
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}
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class json_exception ["basic_json::exception"] {
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+const int id
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+const char* what() const
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}
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class json_parse_error ["basic_json::parse_error"] {
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+const std::size_t byte
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}
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class json_invalid_iterator ["basic_json::invalid_iterator"]
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class json_type_error ["basic_json::type_error"]
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class json_out_of_range ["basic_json::out_of_range"]
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class json_other_error ["basic_json::other_error"]
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std_exception <|-- json_exception
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json_exception <|-- json_parse_error
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json_exception <|-- json_invalid_iterator
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json_exception <|-- json_type_error
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json_exception <|-- json_out_of_range
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json_exception <|-- json_other_error
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style json_parse_error fill:#CCCCFF
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```
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## Member functions
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- **what** - returns explanatory string
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## Member variables
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- **id** - the id of the exception
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- **byte** - byte index of the parse error
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## Notes
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For an input with n bytes, 1 is the index of the first character and n+1 is the index of the terminating null byte or the end of file. This also holds true when reading a byte vector for binary formats.
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## Examples
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Example
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The following code shows how a `parse_error` exception can be caught.
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```
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#include <iostream>
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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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try
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{
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// parsing input with a syntax error
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json::parse("[1,2,3,]");
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}
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catch (const json::parse_error& e)
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{
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// output exception information
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std::cout << "message: " << e.what() << '\n'
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<< "exception id: " << e.id << '\n'
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<< "byte position of error: " << e.byte << std::endl;
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}
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}
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```
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Output:
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```
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message: [json.exception.parse_error.101] parse error at line 1, column 8: syntax error while parsing value - unexpected ']'; expected '[', '{', or a literal
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exception id: 101
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byte position of error: 8
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```
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## See also
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- [`exception`](https://json.nlohmann.me/api/basic_json/exception/index.md) for the base class of all exceptions thrown by the library
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- [List of parse errors](https://json.nlohmann.me/home/exceptions/#parse-errors)
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- [`invalid_iterator`](https://json.nlohmann.me/api/basic_json/invalid_iterator/index.md) for exceptions indicating errors with iterators
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- [`type_error`](https://json.nlohmann.me/api/basic_json/type_error/index.md) for exceptions indicating executing a member function with a wrong type
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- [`out_of_range`](https://json.nlohmann.me/api/basic_json/out_of_range/index.md) for exceptions indicating access out of the defined range
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- [`other_error`](https://json.nlohmann.me/api/basic_json/other_error/index.md) for exceptions indicating other library errors
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## Version history
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- Since version 3.0.0.
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