support bazel complie this project and format code.

practical_exercises/key_exercises/try.cpp

@@ -0,0 +1,25 @@
+/* 异常捕获.cpp */
+#include <iostream>
+using namespace std;
+//函数异常可以抛出去由主函数来处理
+void fun(int x) {
+  try {
+    if (x == 0)
+      throw "异常";
+  } catch (...) {
+    cout << "in fun" << endl;
+    throw 1;
+  }
+}
+
+int main(int argc, char const *argv[]) {
+
+  try {
+    fun(0);
+  } catch (int n) {
+    cout << "in main" << endl;
+  }
+
+  
+  return 0;
+}