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1.4 KiB
1.4 KiB
FAQ
Parsing
How can I parse from a string?
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?
std::ifstream i("your_file.json");
json j = json::parse(i);
Serialization
How can I serialize a JSON value
std::cout << j << std::endl;
This is equivalent to
std::string s = j.dump();
std::cout << s << std::endl;
How can I pretty-print a JSON value
std::cout << std::setw(4) << j << std::endl;
This is equivalent to
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?
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?
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:
for (auto it : json::iteration_wrapper(j))
{
// the value
json &val = it.value();
// the key (for objects)
const std::string &key = it.key();
}