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features/creating_values/index.md
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@@ -52,6 +52,24 @@ json array_of_objects = json::array({{"key", "value"}}); // [{"key":"value"}]
Related to this, single-element brace initialization such as `json j{value};` wraps the element in a single-element **array** by default, and its behavior even differs between compilers. See the [FAQ](https://json.nlohmann.me/home/faq/#brace-initialization-yields-arrays) for details and the opt-in [`JSON_BRACE_INIT_COPY_SEMANTICS`](https://json.nlohmann.me/api/macros/json_brace_init_copy_semantics/index.md) macro.
### What does this produce?
The following table shows how some common spellings are interpreted. When in doubt, use `json::array()`, `json::object()`, or the `json(value)` form with parentheses.
| code | result | note |
| ------------------------------------ | ----------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `json j = {};` / `json j{};` | `null` | use `json::object()` or `json::array()` |
| `json j = json::object();` | `{}` | |
| `json j = json::array();` | `[]` | |
| `json j(true);` | `true` | parentheses create the value itself |
| `json j = {true};` | `[true]` | braces create a one-element array (`json j{true};` depends on the compiler, see the [FAQ](https://json.nlohmann.me/home/faq/#brace-initialization-yields-arrays)) |
| `json j = {{"a", 1}};` | `{"a":1}` | all elements are `[string, value]` pairs: object |
| `json j = {{"a", 1}, {"b"}};` | `[["a",1],["b"]]` | one element is not a pair: array |
| `json j = {{"a", 1}, 2};` | `[["a",1],2]` | a plain value among pairs: array |
| `json j = {{"a", 1, 2}};` | `[["a",1,2]]` | a three-element list is not a pair: array |
| `json j = "{\"a\":1}";` | `"{\"a\":1}"` | a string **value**; it is not parsed |
| `json j = json::parse("{\"a\":1}");` | `{"a":1}` | parse text with `parse` or `_json` |
## Building incrementally
A value can also be built up piece by piece. Accessing a non-existing object key or array index with [`operator[]`](https://json.nlohmann.me/features/element_access/unchecked_access/index.md) creates the element on the fly:
@@ -76,7 +94,7 @@ Example
#include <iomanip>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
using nlohmann::json;
using namespace nlohmann::literals;
int main()