php检查用户输入是否不是空格

Question

I have the following code to check user input:

if(isset($_POST['block_name']) && !empty($_POST['block_name'])) {
    $block->name = trim($_POST['block_name']);
}

But it accepts SPACE as valid input, so I changed to this:

if(isset($_POST['block_name']) && !empty($_POST['block_name']) && trim($_POST['block_name'])!='') {
        $block->name = trim($_POST['block_name']);
    }

I have found on web that I can use !=false as well. What is the difference and which is recommended.

Answer 1

'' equals false in a loose comparison, so there's no real difference. Since '0' also equals false though, you may want to make your check more strict. empty is also just checking for false without triggering an error if the variable is not set. So isset && !empty is redundant to begin with.

Use:

if (isset($_POST['block_name']) && strlen(trim($_POST['block_name'])) > 0)