Experiment 2: stack

Summary of common problems in running the basic operation code of stack
1. compiler ： It is best to DEV
2. File suffix ：.cpp（ Because stack application functions often use references &）
3.flushall（） function ：scanf The operation of convection follows the principle of type matching , If the type doesn't match , It will not read the input stream . So the input stream will stay , If the input stream is not empty ,scanf Don't wait for user input , The solution is to manually clear zd Except input stream , You can use flushall() Function implementation .
4.typedef： It is equivalent to renaming a data type name , Reading code is a little more concise
5. You can put default Delete the sentence