var_dump() displays values along with data types as output. print_r() displays only value as output. It does not have any return type. It will return a value that is in string format.
Echo is for display, while return is used to store a value, which may or may not be used for display or other use.
It is a built-in function in print_r in PHP that is used to print or display the contents of a variable. It essentially prints human-readable data about a variable. The value of the variable will be printed if it is a string, integer, or float.
print
and echo
are more or less the same; they are both language constructs that display strings. The differences are subtle: print
has a return value of 1 so it can be used in expressions whereas echo
has a void
return type; echo
can take multiple parameters, although such usage is rare; echo
is slightly faster than print
. (Personally, I always use echo
, never print
.)
var_dump
prints out a detailed dump of a variable, including its type and the type of any sub-items (if it's an array or an object). print_r
prints a variable in a more human-readable form: strings are not quoted, type information is omitted, array sizes aren't given, etc.
var_dump
is usually more useful than print_r
when debugging, in my experience. It's particularly useful when you don't know exactly what values/types you have in your variables. Consider this test program:
$values = array(0, 0.0, false, '');
var_dump($values);
print_r ($values);
With print_r
you can't tell the difference between 0
and 0.0
, or false
and ''
:
array(4) {
[0]=>
int(0)
[1]=>
float(0)
[2]=>
bool(false)
[3]=>
string(0) ""
}
Array
(
[0] => 0
[1] => 0
[2] =>
[3] =>
)
echo
No return value
e.g. echo "String 1", "String 2"
Returns 1
, so it can be used in an expression
e.g. print "Hello"
or, if ($expr && print "foo")
print_r()
var_dump()
print_r()
, for example it also prints the type of valuesvar_export()
print_r()
and var_dump()
- resulting output is valid PHP code!Notes:
print
can be used in an expression, I recommend people avoid doing so, because it is bad for code readability (and because it's unlikely to ever be useful). The precedence rules when it interacts with other operators can also be confusing. Because of this, I personally don't ever have a reason to use it over echo
.echo
and print
are language constructs, print_r()
and var_dump()
/var_export()
are regular functions. You don't need parentheses to enclose the arguments to echo
or print
(and if you do use them, they'll be treated as they would in an expression).var_export()
returns valid PHP code allowing values to be read back later, relying on this for production code may make it easier to introduce security vulnerabilities due to the need to use eval()
. It would be better to use a format like JSON instead to store and read back values. The speed will be comparable.Just to add to John's answer, echo
should be the only one you use to print content to the page.
print
is slightly slower. var_dump()
and print_r()
should only be used to debug.
Also worth mentioning is that print_r()
and var_dump()
will echo by default, add a second argument to print_r()
at least that evaluates to true to get it to return instead, e.g. print_r($array, TRUE)
.
The difference between echoing and returning are:
The difference between echo, print, print_r and var_dump is very simple.
echo
echo is actually not a function but a language construct which is used to print output. It is marginally faster than the print.
echo "Hello World"; // this will print Hello World
echo "Hello ","World"; // Multiple arguments - this will print Hello World
$var_1=55;
echo "$var_1"; // this will print 55
echo "var_1=".$var_1; // this will print var_1=55
echo 45+$var_1; // this will print 100
$var_2="PHP";
echo "$var_2"; // this will print PHP
$var_3=array(99,98,97) // Arrays are not possible with echo (loop or index value required)
$var_4=array("P"=>"3","J"=>"4"); // Arrays are not possible with echo (loop or index value required)
You can also use echo statement with or without parenthese
echo ("Hello World"); // this will print Hello World
Just like echo construct print is also a language construct and not a real function. The differences between echo and print is that print only accepts a single argument and print always returns 1. Whereas echo has no return value. So print statement can be used in expressions.
print "Hello World"; // this will print Hello World
print "Hello ","World"; // Multiple arguments - NOT POSSIBLE with print
$var_1=55;
print "$var_1"; // this will print 55
print "var_1=".$var_1; // this will print var_1=55
print 45+$var_1; // this will print 100
$var_2="PHP";
print "$var_2"; // this will print PHP
$var_3=array(99,98,97) // Arrays are not possible with print (loop or index value required)
$var_4=array("P"=>"3","J"=>"4"); // Arrays are not possible with print (loop or index value required)
Just like echo, print can be used with or without parentheses.
print ("Hello World"); // this will print Hello World
print_r
The print_r() function is used to print human-readable information about a variable. If the argument is an array, print_r() function prints its keys and elements (same for objects).
print_r ("Hello World"); // this will print Hello World
$var_1=55;
print_r ("$var_1"); // this will print 55
print_r ("var_1=".$var_1); // this will print var_1=55
print_r (45+$var_1); // this will print 100
$var_2="PHP";
print_r ("$var_2"); // this will print PHP
$var_3=array(99,98,97) // this will print Array ( [0] => 1 [1] => 2 [2] => 3 )
$var_4=array("P"=>"3","J"=>"4"); // this will print Array ( [P] => 3 [J] => 4 )
var_dump
var_dump function usually used for debugging and prints the information ( type and value) about a variable/array/object.
var_dump($var_1); // this will print int(5444)
var_dump($var_2); // this will print string(5) "Hello"
var_dump($var_3); // this will print array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(3) }
var_dump($var_4); // this will print array(2) { ["P"]=> string(1) "3" ["J"]=> string(1) "4" }
echo
Not having return type
print
Have return type
print_r()
Outputs as formatted,
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