amorfo77/json
1
0
Fork 0
mirror of https://github.com/nlohmann/json.git synced 2026-10-05 22:20:30 +00:00
Code Issues Packages Projects Releases Wiki Activity

deploy: d8d47be4a5

Browse Source
This commit is contained in:
nlohmann
2026-10-04 15:46:44 +00:00
parent 19f538472d
commit c51ca275d0
374 changed files with 1998 additions and 551 deletions
Download Patch File Download Diff File Expand all files Collapse all files
features/assertions.md
+31 -7
View File
@@ -16,14 +16,15 @@ before including the `json.hpp` header.
## Function with runtime assertions
### Unchecked object access to a const value
### Unchecked access to a const value
Function [`operator[]`](../api/basic_json/operator%5B%5D.md) implements unchecked access for objects. Whereas a missing
key is added in the case of non-const objects, accessing a const object with a missing key is undefined behavior (think
of a dereferenced null pointer) and yields a runtime assertion.
Function [`operator[]`](../api/basic_json/operator%5B%5D.md) implements unchecked access for arrays and objects. Whereas
a missing element is added in the case of non-const values, accessing a const value with a missing object key or an
invalid array index is undefined behavior (think of a dereferenced null pointer) and yields a runtime assertion. This
also applies to a [JSON pointer](json_pointer.md) that refers to a missing key or an invalid index.
If you are not sure whether an element in an object exists, use checked access with the
[`at` function](../api/basic_json/at.md) or call the [`contains` function](../api/basic_json/contains.md) before.
If you are not sure whether an element exists, use checked access with the [`at` function](../api/basic_json/at.md)
or call the [`contains` function](../api/basic_json/contains.md) before.
See also the documentation on [element access](element_access/index.md).
@@ -46,7 +47,30 @@ See also the documentation on [element access](element_access/index.md).
Output:
```
Assertion failed: (m_value.object->find(key) != m_value.object->end()), function operator[], file json.hpp, line 2144.
Assertion failed: (it != m_data.m_value.object->end()), function operator[], file json.hpp, line 28795.
```
??? example "Example 2: Invalid array index in a JSON pointer"
The following code will trigger an assertion at runtime:
```cpp
#include <nlohmann/json.hpp>
using json = nlohmann::json;
using namespace nlohmann::literals;
int main()
{
const json j = {{"array", {1, 2, 3}}};
auto v = j["/array/5"_json_pointer];
}
```
Output:
```
Assertion failed: (idx < m_data.m_value.array->size()), function operator[], file json.hpp, line 28758.
```
### Constructing from an uninitialized iterator range