1
0
mirror of https://github.com/nlohmann/json synced 2024-11-22 12:00:05 +00:00

📝 some documentation

This commit is contained in:
Niels Lohmann 2017-10-27 16:07:04 +02:00
parent 734e2b73cf
commit 61cc07ff38
No known key found for this signature in database
GPG Key ID: 7F3CEA63AE251B69
3 changed files with 96 additions and 10 deletions

View File

@ -107,7 +107,7 @@ WARN_LOGFILE =
# Configuration options related to the input files
#---------------------------------------------------------------------------
INPUT = ../src/json.hpp \
index.md
index.md faq.md
INPUT_ENCODING = UTF-8
FILE_PATTERNS =
RECURSIVE = NO

87
doc/faq.md Normal file
View File

@ -0,0 +1,87 @@
# FAQ
## Parsing
### How can I parse from a string?
```cpp
json j = json::parse("[1,2,3,4]");
```
You can pass string literals (as above), `std::string`, `const char*` or byte containers such as `std::vector<uint8_t>`.
### How can I parse from a file?
```cpp
std::ifstream i("your_file.json");
json j = json::parse(i);
```
## Serialization
### How can I serialize a JSON value
```cpp
std::cout << j << std::endl;
```
This is equivalent to
```cpp
std::string s = j.dump();
std::cout << s << std::endl;
```
### How can I pretty-print a JSON value
```cpp
std::cout << std::setw(4) << j << std::endl;
```
This is equivalent to
```cpp
std::string s = j.dump(4);
std::cout << s << std::endl;
```
The number `4` denotes the number of spaces used for indentation.
## Iterating
### How can I iterate over a JSON value?
```cpp
for (json& val : j)
{
// val is a reference for the current value
}
```
This works with any JSON value, also primitive values like numbers.
### How can I access the keys when iterating over a JSON object?
```cpp
for (auto it = j.begin(); it != j.end(); ++it)
{
// the value
json &val = it.value();
// the key (for objects)
const std::string &key = it.key();
}
```
You can also use an iteration wrapper and use range for:
```cpp
for (auto it : json::iteration_wrapper(j))
{
// the value
json &val = it.value();
// the key (for objects)
const std::string &key = it.key();
}
```

View File

@ -8160,13 +8160,11 @@ class basic_json
@brief per-element parser callback type
With a parser callback function, the result of parsing a JSON text can be
influenced. When passed to @ref parse(std::istream&, const
parser_callback_t) or @ref parse(const CharT, const parser_callback_t),
it is called on certain events (passed as @ref parse_event_t via parameter
@a event) with a set recursion depth @a depth and context JSON value
@a parsed. The return value of the callback function is a boolean
indicating whether the element that emitted the callback shall be kept or
not.
influenced. When passed to @ref parse, it is called on certain events
(passed as @ref parse_event_t via parameter @a event) with a set recursion
depth @a depth and context JSON value @a parsed. The return value of the
callback function is a boolean indicating whether the element that emitted
the callback shall be kept or not.
We distinguish six scenarios (determined by the event type) in which the
callback function can be called. The following table describes the values
@ -8203,8 +8201,7 @@ class basic_json
should be kept (`true`) or not (`false`). In the latter case, it is either
skipped completely or replaced by an empty discarded object.
@sa @ref parse(std::istream&, parser_callback_t) or
@ref parse(const CharT, const parser_callback_t) for examples
@sa @ref parse for examples
@since version 1.0.0
*/
@ -12948,6 +12945,8 @@ class basic_json
@param[in] cb a parser callback function of type @ref parser_callback_t
which is used to control the deserialization by filtering unwanted values
(optional)
@param[in] allow_exceptions whether to throw exceptions in case of a
parse error (optional, true by default)
@return result of the deserialization