Multidimensional arrays through functions (PHP) - php

Question

Complete beginner here.
If I have a multi-dimensional array:
$main_array = array(
$sub_array1('name','value1','value2'),
$sub_array2('name','value1','value2'),
$sub_array3('name','value1','value2')
);
...and a user function:
function multiply($a, $b) {
$result = $a * $b};
return $result;
};
What's the best method to loop each sub-array through the function such that $a is value1 and $b is value2? How can I get the outcome to look something like:
Name1: result1
Name2: result2
Name3: result3
I'm currently fiddling with the following:
foreach($main_array as $x) {
print_r(multiply($x['value1'], $x['value2']));
};
...which is wrong in syntax, logic, or both.

Answer 1

First your array creation is incorrect
$main_array = array(
array('fred','1','2'),
array('bill','3','4'),
array('jane','5','6')
);
Now this array can be processed like this and the sub arrays which are not associative arrays and therefore are not name->value types have to be processed using their indexes
foreach ( $main_array as $sub_array ) {
echo $sub_array[0] , ' = ' . ($sub_array[1] * $sub_array[2]);
}
And will produce the output:
fred = 2
bill = 12
jane = 30
Note: print_r() is used to display arrays & onjects, you need to use echo or print to display scalar values.
Also there is no multiply function, just use old fashioned maths eg $x * $y

Answer 2

print_r will display a readable version of a variable, such as an object, array etc. Since you are looping through an array to display a value in a certain format - this will not work.
To get the intended result, a simple change is required:
foreach($main_array as $x) {
echo $x['name'] . multiply($x['value1'], $x['value2']);
};
Or ditch the user defined function 'multiply' for basic maths.
foreach($main_array as $x) {
echo $x['name'] . ($x['value1'] * $x['value2']);
};
Edit:
Also to Dagon's point above in the comments - the array you are using is not valid. The syntax is wrong and you aren't using named keys but you are referencing them. Change the structure like so:
$name = "Value";
$value = 10;
$main_array = array(
array('name' => $name, 'value1' => $value, 'value2' => $value),
array('name' => $name, 'value1' => $value, 'value2' => $value),
array('name' => $name, 'value1' => $value, 'value2' => $value),
);
Alternatively if you wanted to make it a bit more readable.
$nameValue = "test";
$value1 = 10;
$value2 = 10;
$subArray1 = [
"name" => $nameValue,
"value1" => $value1,
"value2" => $value2
];
$subArray2 = [
"name" => $nameValue,
"value1" => $value1,
"value2" => $value2
];
$subArray3 = [
"name" => $nameValue,
"value1" => $value1,
"value2" => $value2
];
$main_array = array($subArray1, $subArray2, $subArray3);
Updated for more completeness & assuming use of user function multiply