php检查isset和value = 0

I am using the CodeIgniter framework to create my web services. I have an optional parameter that I want to set its value according to:-

• if it exists and has value 0, var2 = a
• else var2 = b

Method 1

    $foo = $this->post('foo');

    if(isset($foo) && $foo == 0) {
        $var2 = 'a';
    } else {
        $var2 = 'b';
    }

Method 2

    $foo = $this->post('foo');

    if(isset($foo)) {
        if ($foo == 0)
            $var2 = 'a';
        else
            $var2 = 'b';
    } else {
        $var2 = 'b';
    }

Both methods are returning $var2 = 'a' when I do not send in foo.

try below, both are same.

$foo = $this->input->post("username");
$var2 = (int)$foo === 0 ? 'a' : 'b';

OR

$foo = $this->input->post("username");

if((int)$foo === 0)
    $var2 = 'a';
else
    $var2 = 'b';

NOTE: you are using isset() to check an empty string. That is why it returns true always.

Hope this helps :)

you not using correct method to getting post value try

$foo = $this->input->post('foo');
if(empty($foo)) {
 $var2 = 'a';
} else {
    $var2 = 'b';
}

$this->input->post()

The function returns FALSE (boolean) if the item you are attempting to retrieve does not exist.

so instead try something like this

if(isset($_POST['foo']) && $_POST['foo'] == 0) {
    $var2 = 'a';
} else {
    $var2 = 'b';
}

or

$foo = $this->input->post('foo');
if($foo && $foo == 0){
    $var2 = 'a';
} else {
    $var2 = 'b';

user this code

$foo = $this->input->post('foo');

if(isset($foo) && $foo == '0') {   

    $var2 = 'a';
} else {
    $var2 = 'b';
} 

echo " variable =". $var2;

Output:

variable = a  // if you enter  0 in foo field

variable = b // if you didn't enter 0 

You have to use single quotes around 0 (Zero) in if condition

if(isset($foo) && $foo == '0')   

$foo = $this->input->post('foo'); var_dump($foo );

check the value of $foo then write candition, may be $foo return false value

Fixed it using === '0'.

$foo = $this->post('foo');

if($foo === '0') {
    $var2 = 'a';
} else {
    $var2 = 'b';
}