在PHP中的随机播放功能

I have 4 variable each . I try to echo each variable with concatenation dot and shuffle them so, it is like that

echo str_shuffle(variable1.vatiable2.var3.var4)

When I echo the value of these variable the last two or one variable do not even appear so it echos like:

Variable1.variable2 only and ignores the values at variable3 and 4, sometimes it only ignores the last variable only

Is the reason the shuffle function? How to solve this and is tere a similar function to shullke that does not produces this error. Thanks in advance.

$var='this';
$var1='pak';
$var2='ist';
$var3='pakistan';

$newvar= $var.$var1.$var2.$var3;

echo str_shuffle($newvar);

First concatenate all variables then store it new var and then shuffle it.