In the collar buckle, you will encounter problems that you will not do. At this time, you can take a look at the official solutions and the comments and solutions written by the big brothers. At this time, if the code is still not particularly understood, it is best to use debug for debugging. It is very good when debugging, and each step of the debugging process can understand the execution process, which is very helpful for the understanding of the code and also helps to improve the ability of the code.
