为什么此函数总是返回false？

Question

I have a very basic question. It's may very poor question but I just want to clear my confusion.

function check_array($user_value,$array)
    {
        foreach ($array as $key => $value) {
            if($value==$user_value)
            {
                return true;
            }
            return false;
        }
        //return false;
    }

Why this function always returning false.

for example If I have $numbers = array(1,2,3) . If I match 2 with this array it should return me true else return me false. But why it's returning always false ?

Answer 1

The return false is in the wrong place, it should be where you commented it out but not in the other place it is.

function check_array($user_value,$array)
    {
        foreach ($array as $key => $value) {
            if($value==$user_value)
            {
                return true;
            }
        }
        return false;
    }

If the return is in the other place, it will return false after failing to find your value in the first array cell.

Answer 2

why it's returning always false ?

Try to "execute" this function yourself acting as a computer.

If the first element of array is equal to $user_value , it will return true. If not - it will move futher down the loop and return false.

Probably, you wanted to check all the elements of array for equality. In this case you need to use this:

function check_array($user_value,$array)
    {
        foreach ($array as $key => $value) {
            if($value==$user_value)
            {
                return true;
            }
        }
        return false;
    }

Answer 3

You dont need to create a function for it when php has already have it in_array

you can use it like in a single line

$result = in_array($user_value,$array)

It will return true if the value is found and false if not found. You need not to loop through the array

Answer 4

You have the return false inside of the loop. That means if the first element isn't a match, it will return false. It won't even check the second element of your array

Answer 5

Your function will be returning false, unless it matches the first value in the array.

This is because at the moment your logic is in the wrong order, and if the first value in the array doesn't match $user_value the function returns false.

You could solve this problem by moving the return false; line of code below the loop. Now the loop will run through all the values in the array. It will return true if it matches one, and if it has checked all the values and there is no match then it will then return false.

function check_array($user_value,$array)
    {
        foreach ($array as $key => $value) {
            if($value==$user_value) return true;
        }
        return false;
    }

This should clear up the logic mistake in your code. However I up-voted Veerendra's in_array() answer as that means there is no need for any loop, cutting down your code.