book: typo fixes (changkun#177)

LaChimere · web-flow · commit 4cb055f6292b · 2021-04-05T23:30:43.000+02:00
diff --git a/book/en-us/04-containers.md b/book/en-us/04-containers.md
@@ -292,7 +292,7 @@ This will iterate over the tuple:
 ```cpp
 for(int i = 0; i != tuple_len(new_tuple); ++i)
     // runtime indexing
-    std::cout << tuple_index(i, new_tuple) << std::endl;
+    std::cout << tuple_index(new_tuple, i) << std::endl;
 ```
 
 ## Conclusion
diff --git a/book/zh-cn/04-containers.md b/book/zh-cn/04-containers.md
@@ -292,7 +292,7 @@ auto tuple_len(T &tpl) {
 // 迭代
 for(int i = 0; i != tuple_len(new_tuple); ++i)
     // 运行期索引
-    std::cout << tuple_index(i, new_tuple) << std::endl;
+    std::cout << tuple_index(new_tuple, i) << std::endl;
 ```
 
 ## 总结
