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