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api/basic_json/is_number_integer/index.md

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+# nlohmann::basic_json::is_number_integer
+
+```
+constexpr bool is_number_integer() const noexcept;
+```
+
+This function returns `true` if and only if the JSON value is a signed or unsigned integer number. This excludes floating-point values.
+
+## Return value
+
+`true` if type is an integer or unsigned integer number, `false` otherwise.
+
+## Exception safety
+
+No-throw guarantee: this member function never throws exceptions.
+
+## Complexity
+
+Constant.
+
+## Examples
+
+Example
+
+The following code exemplifies `is_number_integer()` for all JSON types.
+
+```
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create JSON values
+    json j_null;
+    json j_boolean = true;
+    json j_number_integer = 17;
+    json j_number_unsigned_integer = 12345678987654321u;
+    json j_number_float = 23.42;
+    json j_object = {{"one", 1}, {"two", 2}};
+    json j_array = {1, 2, 4, 8, 16};
+    json j_string = "Hello, world";
+    json j_binary = json::binary({1, 2, 3});
+
+    // call is_number_integer()
+    std::cout << std::boolalpha;
+    std::cout << j_null.is_number_integer() << '\n';
+    std::cout << j_boolean.is_number_integer() << '\n';
+    std::cout << j_number_integer.is_number_integer() << '\n';
+    std::cout << j_number_unsigned_integer.is_number_integer() << '\n';
+    std::cout << j_number_float.is_number_integer() << '\n';
+    std::cout << j_object.is_number_integer() << '\n';
+    std::cout << j_array.is_number_integer() << '\n';
+    std::cout << j_string.is_number_integer() << '\n';
+    std::cout << j_binary.is_number_integer() << '\n';
+}
+```
+
+Output:
+
+```
+false
+false
+true
+true
+false
+false
+false
+false
+false
+```
+
+## See also
+
+- [is_number()](https://json.nlohmann.me/api/basic_json/is_number/index.md) check if the value is a number
+- [is_number_unsigned()](https://json.nlohmann.me/api/basic_json/is_number_unsigned/index.md) check if the value is an unsigned integer number
+- [is_number_float()](https://json.nlohmann.me/api/basic_json/is_number_float/index.md) check if the value is a floating-point number
+
+## Version history
+
+- Added in version 1.0.0.
+- Extended to also return `true` for unsigned integers in 2.0.0.