PHP Math random number calculation - php

Question

Please check my code:
<?php
$operarors = array( '+', '-', '*' );
$randOperator = array($operarors[rand(0,2)], $operarors[rand(0,2)]);
$num1 = rand(0,10);
$num2 = rand(0,10);
$num3 = rand(0,10);
$result = $num1.$randOperator[0].$num2.$randOperator[1].$num3;
echo "The math: $num1 $randOperator[0] $num2 $randOperator[1] $num3 = $result";
?>
In the code above, I am not getting my total number of result.
Suppose I am getting 3+4*5, the output should be 23, but it is showing the string 3+4*5.
Help me please.

Answer 1

You can't just concatenate the operators like that. I suggest doing something like this:
<?php
function operate($op1, $operator, $op2) {
switch ($operator) {
case "+":
return $op1 + $op2;
case "-":
return $op1 - $op2;
case "*":
return $op1 * $op2;
}
}
$operators = array( '+', '-', '*' );
// performs calculations with correct order of operations
function calculate($str) {
global $operators;
// we go through each one in order of precedence
foreach ($operators as $operator) {
$operands = explode($operator, $str, 2);
// if there's only one element in the array, then there wasn't that operator in the string
if (count($operands) > 1) {
return operate(calculate($operands[0]), $operator, calculate($operands[1]));
}
}
// there weren't any operators in the string, assume it's a number and return it so it can be operated on
return $str;
}
$randOperator = array($operators[rand(0,2)], $operators[rand(0,2)]);
$num1 = rand(0,10);
$num2 = rand(0,10);
$num3 = rand(0,10);
$str = "$num1 $randOperator[0] $num2 $randOperator[1] $num3";
echo "$str = ", calculate($str), PHP_EOL;

Answer 2

As #AndreaFaulds said, or use callbacks: (though using array_reduce and all this array pointer magic is not necessary).
<?php
$ops = [
'+' => function ($op1, $op2) { return $op1 + $op2; },
'*' => function ($op1, $op2) { return $op1 * $op2; },
'-' => function ($op1, $op2) { return $op1 - $op2; }
];
$nums = [rand(0, 10), rand(0, 10), rand(0, 10)];
$operators = [array_rand($ops), array_rand($ops)];
$initial = array_shift($nums);
$result = array_reduce($nums, function ($accumulate, $num) use (&$operators, $ops) {
return $ops[each($operators)[1]]($accumulate, $num);
}, $initial);
Note, [] short array syntax has a version requirement of PHP 5.4+.

Answer 3

You should use the + operator instead of the . operator. The . just pastes it together as if the values were strings.