Basic PHP learning basics (required by Cainiao)

The output value "123 '123' is not" 123 $ ". Although it is '$ A', the variable placed under double quotation marks is still replaced. I. PHP script code mark

PHP scripts are the content of a pair of special tags in the file. for example, ASP is "<%... %>", and PHP can be viewed as" ".

However, to adapt to XML standards to embed PHP into XML or XHTML, PHP does not recommend that you use the" ", But it is recommended to use long format mark" "

In addition, PHP code blocks support