fix(exercise): 解决 18 题在 gcc 上自动通过的问题

Signed-off-by: YdrMaster <[email protected]>

exercises/18_function_template/main.cpp

@@ -6,11 +6,15 @@ int plus(int a, int b) {
     return a + b;
 }
 
-// ---- 不要修改以下代码 ----
 int main(int argc, char **argv) {
-    ASSERT(plus(1, 2) == 3, "plus two int");
-    ASSERT(plus(1u, 2u) == 3u, "plus two unsigned int");
-    ASSERT(plus(1.f, 2.f) == 3.f, "plus two float");
-    ASSERT(plus(1.0, 2.0) == 3.0, "plus two double");
+    ASSERT(plus(1, 2) == 3, "Plus two int");
+    ASSERT(plus(1u, 2u) == 3u, "Plus two unsigned int");
+
+    // THINK: 浮点数何时可以判断 ==？何时必须判断差值？
+    ASSERT(plus(1.25f, 2.5f) == 3.75f, "Plus two float");
+    ASSERT(plus(1.25, 2.5) == 3.75, "Plus two double");
+    // TODO: 修改判断条件使测试通过
+    ASSERT(plus(0.1, 0.2) == 0.3, "How to make this pass?");
+
     return 0;
 }