Indirect reference, connection string, and connection assignment operator of variables in php getting started Variables

[1] indirect reference of variables:

<? Php $ a = 'B'; $ a = '000000'; echo $ B;?>

 

The output above is 123

We can see that there is another $ in the second line of code, and the variable is accessed through the specified name, the specified name is stored in $ a ('B, change the value of $ B to 123. Therefore, such $ B variables are created and assigned values.

By adding the $ tag before the variable, you can increase the number of references at will.

[2] connection string: concatenates a string into a new merged string by using a concatenation operator (.) in English.

<? Php $ a = 'php5 '; $ B = 'powerfully'; echo $ a. $ B;?>

 

To give us a better understanding of the connection string, we changed it based on the above example (PHP5: Powerful 2014)

In this example, quotation marks, spaces, and numbers are added. Below we will use two methods to write, the specific difference I found:

<? Php $ c = $ a. ':'. $ B. '000000'; $ c = $ a. ':'. $ B. '. 2014;?>

 

[3] Join value assignment operator: if only one value is connected to another value, you can use the join value assignment operator (. = ). The following two statements are equivalent:

<? Php $ title = $ title. $ subtitle; $ title. = $ subtitle;?>