PHP, Calculation Key in array - php

Question

i have an array like this
Array
(
[0] => LK10110000
[1] => +
[2] => LK10120000
[3] => -
[4] => LK10130000
)
from that array I want to do a query based on the following sequence of array calculations
expected results :
Value = ResultMysql [LK10110000] + ResultMysql [LK10120000] - ResultMysql [LK10130000]`

Answer 1

From your question and the comments I understand you have a string that contains an expression and you need to run some queries and compute a result base on the expression. And the problem is that you don't know the expression in advance.
I assume your expression contains only addition and subtraction.
If it also contains multiplication or division, parentheses, functions or other operators then the rest of the answer does not apply, it needs more complex code to handle operators precedence, parentheses and function calls.
The idea
Initialize the variable holding the final result with 0.
Split the string into pieces as you already did.
Prepend a + sign to the array of pieces.
Take the first two pieces from the array. The first one is the sign, the second is the variable.
Compose and run the query using the variable as parameter.
Add or subtract the value returned by the query to the final result (check the sign retrieved on step 4 to know if it's add or subtract).
If there still are pieces not processed in the array, repeat from step 4.
The code
The code is less and more clear than the above description:
// This is the input expression
$expression = 'LK10110000; +; LK10120000; -; LK10130000';
// Step 1
$total = 0;
// Step 2
$pieces = explode(';', $pieces);
if (count($pieces) % 2 != 1) {
// The expression is incorrect; handle the situation somehow
//
// A valid expression must contain an odd number of items
// (alternating value and operator, starting and ending with a value)
}
// Extra processing: remove the padding spaces from around the values
// to ensure testing the sign against '-' works correctly
$pieces = array_map('trim', $pieces);
// Step 3
array_unshift($pieces, '+');
// Step 4
do {
$sign = array_unshift($pieces);
$value = array_unshift($pieces);
// Step 5
// ... use $value here to generate and run the query
// ... put the value returned by the query in variable $result
$result = 1; // <-- replace this line
// Step 6
if ($sign === '+') {
$total += $result;
} elseif ($sign === '-') {
$total -= $result;
} else {
// This is an error in the expression; handle it somehow
}
// Step 7
} while (count($pieces));
// The output is in $total
echo($total);
Remarks
If the queries do not return a single numeric value but a set of records ($value is an array of scalar, arrays or objects) then adjust the code on step 6 and use the appropriate merging of $value into $total. Also initialize $total with the correct array of scalars/arrays/objects.
The exact definition of "appropriate merging" depends on the rules of your application. To achieve it you probably must iterate over the elements of $value and for each one, find the corresponding element in $total and update it or insert it if not already present.