amorfo77/json
1
0
Fork 0
mirror of https://github.com/nlohmann/json.git synced 2026-10-03 21:20:30 +00:00
Code Issues Packages Projects Releases Wiki Activity

deploy: 63c10a51fc

Browse Source
This commit is contained in:
nlohmann
2026-10-03 05:43:12 +00:00
parent 2aaa1d24ef
commit a410b4f40f
741 changed files with 8115 additions and 2252 deletions
Download Patch File Download Diff File Expand all files Collapse all files
features/parsing/parse_exceptions/index.html
+11 -10
View File
File diff suppressed because one or more lines are too long
features/parsing/parse_exceptions/index.md
+11 -8
View File
@@ -18,7 +18,7 @@ In case exceptions are undesired or not supported by the environment, there are
## Switch off exceptions
The `parse()` function accepts a `bool` parameter `allow_exceptions` which controls whether an exception is thrown when a parse error occurs (`true`, default) or whether a discarded value should be returned (`false`).
The [`parse()`](https://json.nlohmann.me/api/basic_json/parse/index.md) function accepts a `bool` parameter `allow_exceptions` which controls whether an exception is thrown when a parse error occurs (`true`, default) or whether a discarded value should be returned (`false`).
```
json j = json::parse(my_input, nullptr, false);
@@ -32,7 +32,7 @@ Note there is no diagnostic information available in this scenario.
## Use accept() function
Alternatively, function `accept()` can be used which does not return a `json` value, but a `bool` indicating whether the input is valid JSON.
Alternatively, function [`accept()`](https://json.nlohmann.me/api/basic_json/accept/index.md) can be used which does not return a `json` value, but a `bool` indicating whether the input is valid JSON.
```
if (!json::accept(my_input))
@@ -57,7 +57,9 @@ bool parse_error(std::size_t position,
The return value indicates whether the parsing should continue, so the function should usually return `false`.
Example
Example: report parse errors without exceptions
The example derives from the library's DOM parser and overrides `parse_error` to print the error instead of throwing. Note the DOM parser is an implementation detail (`nlohmann::detail`) and may change between releases; see [Do not use the `detail` namespace](https://json.nlohmann.me/integration/migration_guide/#do-not-use-the-detail-namespace).
```
#include <iostream>
@@ -65,18 +67,19 @@ Example
using json = nlohmann::json;
class sax_no_exception : public nlohmann::detail::json_sax_dom_parser<json>
// a DOM parser that reports parse errors instead of throwing
class sax_no_exception : public nlohmann::detail::json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type>
{
public:
sax_no_exception(json& j)
: nlohmann::detail::json_sax_dom_parser<json>(j, false)
explicit sax_no_exception(json& j)
: nlohmann::detail::json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type>(j, false)
{}
bool parse_error(std::size_t position,
const std::string& last_token,
const json::exception& ex)
{
std::cerr << "parse error at input byte " << position << "\n"
std::cout << "parse error at input byte " << position << "\n"
<< ex.what() << "\n"
<< "last read: \"" << last_token << "\""
<< std::endl;
@@ -94,7 +97,7 @@ int main()
bool parse_result = json::sax_parse(myinput, &sax);
if (!parse_result)
{
std::cerr << "parsing unsuccessful!" << std::endl;
std::cout << "parsing unsuccessful!" << std::endl;
}
std::cout << "parsed value: " << result << std::endl;