: This article mainly introduces the difficulty of PHP. if you are interested in the PHP Tutorial, you can refer to it. PHP version: PHP5> = PHP5.2.0
Namespace is a way to encapsulate things,
Use namespace: relative file path, relative script path of the current working path;
: Relative subdirectory path, relative subdirectory path of the current working path;
: Jedi path: \ namespace \ directory \ to \ file
Empty () function: determines whether a variable is null. if it is null, the condition is that the variable does not exist or the value of the variable is false;
Use the expression! Isset ($ var) | $ var = false;
Before PHP5.5, only variable names and expressions are supported,
Therefore, empty (trim (var) is incorrect in syntax;
Isset ($ var): determines whether the variable is set and the set value is not NULL;
The above introduces the PHP solution, including some content, and hopes to help those who are interested in the PHP Tutorial.
