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api/json_pointer/empty/index.md

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+# nlohmann::json_pointer::empty
+
+```
+bool empty() const noexcept;
+```
+
+Return whether the pointer points to the root document.
+
+## Return value
+
+`true` iff the JSON pointer points to the root document.
+
+## Exception safety
+
+No-throw guarantee: this function never throws exceptions.
+
+## Complexity
+
+Constant.
+
+## Examples
+
+Example
+
+The example shows the result of `empty` for different JSON Pointers.
+
+```
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // different JSON Pointers
+    json::json_pointer ptr0;
+    json::json_pointer ptr1("");
+    json::json_pointer ptr2("/foo");
+    json::json_pointer ptr3("/foo/0");
+
+    // call empty()
+    std::cout << std::boolalpha
+              << "\"" << ptr0 << "\": " << ptr0.empty() << '\n'
+              << "\"" << ptr1 << "\": " << ptr1.empty() << '\n'
+              << "\"" << ptr2 << "\": " << ptr2.empty() << '\n'
+              << "\"" << ptr3 << "\": " << ptr3.empty() << std::endl;
+}
+```
+
+Output:
+
+```
+"": true
+"": true
+"/foo": false
+"/foo/0": false
+```
+
+## Version history
+
+Added in version 3.6.0.