deploy: 94fe31eb9b

examples/no_exceptions_access.cpp

@@ -0,0 +1,43 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    json j = json::parse(R"({"name": "Mary", "age": 42})");
+
+    // look up the key, then test the type: neither step throws
+    const auto keys = {"name", "age", "city"};
+    for (const char* key : keys)
+    {
+        const auto it = j.find(key);
+        if (it == j.end())
+        {
+            std::cout << key << ": missing\n";
+        }
+        else if (it->is_string())
+        {
+            std::cout << key << ": string \"" << it->get_ref<const std::string&>() << "\"\n";
+        }
+        else
+        {
+            std::cout << key << ": not a string, but " << it->type_name() << '\n';
+        }
+    }
+
+    // get_ptr returns a null pointer if the value has another type
+    const std::string* name = j["name"].get_ptr<const std::string*>();
+    const std::string* age = j["age"].get_ptr<const std::string*>();
+    std::cout << "get_ptr<string*>: name = " << (name != nullptr) << ", age = " << (age != nullptr) << '\n';
+
+    // value() is NOT exception-free: it throws if the key exists with a different type
+    try
+    {
+        std::cout << j.value("name", 0) << '\n';
+    }
+    catch (const json::type_error& e)
+    {
+        std::cout << e.what() << '\n';
+    }
+}