Php string cast vs strval function which should I use?

What is the difference between doing a string cast and strval in php ?

开发者_运维技巧

1. strval($value);

2. (string)$value;

http://www.php.net/manual/en/language.types.string.php#language.types.string.casting

A value can be converted to a string using the (string) cast or the strval() function.

Looks the same to me.

They are generally interchangeable because PHP uses automatic type conversion and a variable's type is determined by the context in which the variable is used.

Some differences are that strval($var) will return the string value of $var while (string)$var is explicitly converting the "type" of $var during evaluation.

Also, from the manual for strval():

$var may be any scalar type or an object that implements the __toString method. You cannot use strval() on arrays or on objects that do not implement the __toString method.

As mentioned by @Lars (string) is generally faster.

One is a function call, the other one is an internal typecast. Without having checked, I'd guess the latter one is faster by few cycles, but shouldn't really make a difference.

I'm not sure how this applies to various versions of PHP, but when looking at the generated opcodes, both variants generate the same opcodes, and thus perform exactly the same.

Input:

<?php
function s1(int $val) {
    return (string)$val;
}
function s2(int $val) {
    return strval($val);
}

Output as generated by https://3v4l.org/3gFWj/vld#output

Function s1:
Finding entry points
Branch analysis from position: 0
1 jumps found. (Code = 62) Position 1 = -2
filename:       /in/3gFWj
function name:  s1
number of ops:  4
compiled vars:  !0 = $val
line     #* E I O op                           fetch          ext  return  operands
-------------------------------------------------------------------------------------
   2     0  E >   RECV                                             !0      
   3     1        MAKE_REF                                         ~1      !0
         2      > RETURN                                                   ~1
   4     3*     > RETURN                                                   null

End of function s1

Function s2:
Finding entry points
Branch analysis from position: 0
1 jumps found. (Code = 62) Position 1 = -2
filename:       /in/3gFWj
function name:  s2
number of ops:  4
compiled vars:  !0 = $val
line     #* E I O op                           fetch          ext  return  operands
-------------------------------------------------------------------------------------
   5     0  E >   RECV                                             !0      
   6     1        MAKE_REF                                         ~1      !0
         2      > RETURN                                                   ~1
   7     3*     > RETURN                                                   null

End of function s2

Late to the party, but according to PHPstorm (string) is faster

There is an advantage of using strval() over (string), Which is we can use strval as a callback function, Something we cannot do with (string).

$arr = [1, 2, 3];
echo(json_encode($arr)); // [1,2,3]
$arr = array_map('strval', $arr);
echo(json_encode($arr)); // ["1","2","3"]