PHP --var_dump () function

When you debug a program, you want to see information about relevant variables, you can call var_dump () function to see.

• var_dump () function is used to output information related variables.
• var_dump () function display configuration information about one or more expressions, including the type and value of the expression. Recursively expand the array values, indented by its structure.
• PHP Version: PHP 4, PHP 5, PHP 7

grammar:

void var_dump ( mixed $expression [, mixed $... ] )

Parameter Description:

$ Expression: variable you want to output.

return value:

No return value.

Example:

<?php
$a = array(1, 2, array("a", "b", "c"));
var_dump($a);
?>

The output is:

array(3) {
  [0]=>int(1)
  [1]=> int(2)
  [2]=>array(3) {
    [0]=>string(1) "a"
    [1]=> string(1) "b"
    [2]=> string(1) "c"
  }
}

Examples

<?php 
 
 $var;
 var_dump($var);
 echo "<br />";
 
 $var1="string123";
 var_dump($var1); 
 echo "<br />";
 
 $var2=123;
 var_dump( $var2); 
 echo "<br />";
 
 $var3=1*2;
 var_dump($var3);
 echo "<br />";
 
 $b = 3.1000;
var_dump($b);
 echo "<br />";
 
 $c = true;
 var_dump($c);
 
 var_dump($var,$var1,$var2,$var3,$b,$c);//也可同时查看几个
?>

The output is:

NULL 
string(9) "string123" 
int(123) 
int(2) 
float(3.1) 
bool(true) 
NULL string(9) "string123" int(123) int(2) float(3.1) bool(true)