diff --git a/function_template.cpp b/function_template.cpp
new file mode 100644
index 0000000..2016fd9
--- /dev/null
+++ b/function_template.cpp
@@ -0,0 +1,31 @@
+#include <iostream>
+#include <cmath>
+
+// 用函数模板求解定积分
+class F1
+{
+public:
+    double fun(double x) { return x * x; }
+};
+class F2
+{
+public:
+    double fun(double x) { return x; }
+};
+
+template <typename T>
+double integrate(T cf, double a, double b, int n = 10000)
+{
+    double result{(cf.fun(a) + cf.fun(b)) / 2};
+    double h{(b - a) / n};
+    for (int i{1}; i < n; i++)
+        result += cf.fun(a + i * h);
+    result *= h;
+    return result;
+}
+
+int main()
+{
+    std::cout << integrate<F1>(F1{}, 0, 1) << '\n';
+    std::cout << integrate<F2>(F2{}, 0, 1);
+}
\ No newline at end of file