Go deep into the usage of var_dump in php

First look at the instance:

Copy codeThe Code is as follows: <? Php
$ A = "alsdflasdf; ";
$ B = var_dump ($ );
Echo "<br> ";
// Var_dump ($ c );
$ D = var_dump ($ c );
Echo "<br> ";
Echo $;
Echo "<br> ";
Echo $ B;
Echo "<br> ";
Output:
String (12) "alsdflasdf;"
NULL
Alsdflasdf;

What does it mean?The var_dump () method is to judge the type and length of a variable and output the value of the variable. If the variable has a value, it is the value of the variable and returns the data type. this function displays the structure information about one or more expressions, including the expression type and value. The array recursively expands the value and displays its structure through indentation.
Format: var_dump (mixed expression [, mixed expression [,...])
Let's look at the var_dump Syntax:
Var_dump (var, var, bar );
Note that the variables in var_dump must exist. If a variable exists but the value is NULL, false is returned. If no variable exists, NULL is returned. he has an output function. You do not need to add other output functions.