PHP variable or statement comments

Comments on variables or statements in the program follow the following principles:
a. Write it on the line before the variable or statement, not on the same line or after it;
b. Comments are in the format of /* */;
c. Each function must be preceded by a comment block. The content includes a brief description of function functions, input/output parameters, expected return values, and error code definitions.
d. Annotate the complete specification.
e. Delete the commented out code, or indicate the special reason why the commented out code still remains in the source code.
Example:

/** 
* @Purpose: 
* 数据库连接用户名 
* @Attribute/Variable Name: db_user_name 
* @Type: string 
*/ 
var db_user_name;