Simple php function working with Undefined offset ?

[Ahmedoooov]

Hello!

I'm starting to learn php and for practice I tried to resolve a simple exercise.

the idea is to write a php function that inputs a tabe and returns +1 if positive numbers in the table are more than the negative ones. and return -1 if negative numbers in the table are more than the positive ones. 0 if they are equal.

 

this is my code for the function starting from line 8

function plusmin ($tab) {
    $n = count($tab);
    $plus = 0;
    $min = 0;
    for ($i = 0; $i <= $n; $i++) {
        if ($tab[$i] > 0){
            $plus++;
        }
        elseif ($tab[$i] < 0){
            $min++;
        }
    }
    if ($plus > $min) {
        $result = "+1";
    }
    elseif ($plus < $min) {
        $result = "-1";
    }
    elseif ($plus == $min){
        $result = "0";
    }
    return $result;
}

and just to test it I created a table manually

$tab[0] = 1;
$tab[1] = -5;
$tab[2] = -4;
$tab[3] = 7;
$tab[4] = -8;
$tab[5] = -3;
$tab[6] = 2;
$tab[7] = 0;
$tab[8] = -6;
$tab[9] = -9;

$k = plusmin($tab);
echo $k;

when I execute it It works, it shows for the case -1

but the browser shows this error

 

Notice: Undefined offset: 10 in C:\Users\ahmed\PhpstormProjects\Exam 2013\tab.php on line 13

line 13 is this one

 if ($tab[$i] > 0){

Notice: Undefined offset: 10 in C:\Users\ahmed\PhpstormProjects\Exam 2013\tab.php on line 16

line 16 is this one

elseif ($tab[$i] < 0){

I dunno what's the problem. and I know it will turn out to be a stupid problem but hey that's how we all learn.

could anyone help?

 

Thanks in advance

 

[QuickOldCar]

function plusmin ($tab) {
$n = (count($tab) -1);//this would be 0 to actual count in your loop, so deduct one, was adding extra
$plus = 0;
$min = 0;
for ($i = 0; $i <= $n; $i++) {
if ($tab[$i] > 0){
$plus++;
}
elseif ($tab[$i] < 0){
$min++;
}
}
if ($plus > $min) {
$result = "+1";
}
elseif ($plus < $min) {
$result = "-1";
}
elseif ($plus == $min){
$result = "0";
}
return $result;
}

Index key 10 does not exist

Edited January 29, 2016 by QuickOldCar

[QuickOldCar]

You could also loop for just less than $n value rather than less or equals $n

function plusmin ($tab) {
        $n = count($tab); 
        $plus = 0;
        $min = 0;
        for ($i = 0; $i < $n; $i++) {
            if ($tab[$i] > 0){
                $plus++;
            }
            elseif ($tab[$i] < 0){
                $min++;
            }
        }
        if ($plus > $min) {
            $result = "+1";
        }
        elseif ($plus < $min) {
            $result = "-1";
        }
        elseif ($plus == $min){
            $result = "0";
        }
        return $result;
    }

[QuickOldCar]

I suppose will mention can use a foreach instead of counting the array and building the for loop

function plusmin ($tab) {
        $plus = 0;
        $min = 0;
        foreach ($tab as $key=>$value) {
            if ($tab[$key] > 0){
                $plus++;
            }
            elseif ($tab[$key] < 0){
                $min++;
            }
        }
        if ($plus > $min) {
            $result = "+1";
        }
        elseif ($plus < $min) {
            $result = "-1";
        }
        elseif ($plus == $min){
            $result = "0";
        }
        return $result;
    }

And for something as simple as this can just loop the array and use it's value.

function plusmin ($tab) {
        $plus = 0;
        $min = 0;
        foreach ($tab as $value) {
            if ($value > 0){
                $plus++;
            }
            elseif ($value < 0){
                $min++;
            }
        }
        if ($plus > $min) {
            $result = "+1";
        }
        elseif ($plus < $min) {
            $result = "-1";
        }
        elseif ($plus == $min){
            $result = "0";
        }
        return $result;
    }

[Ahmedoooov]

Thank you so much I knew it would turn out to be a stupid mistake

yeah 'foreach' seems a better option than just 'for'