如何在完成php页面之前确保满足每个条件？

Question

so say I have the php:

if(a === x)
{
    echo "a";
}

if(b === y)
{
    echo "b";
}

if(c === z)
{
    echo "c";
}

If a = x and b = y but c doesn't = z. Is there a way to stop a and b being "echoed"?

and the same for if a = x but b doesn't = y and c = z. Is there a way to stop a and c being "echoed"?

---

I know that if a doesn't = x and thus you don't want b and c to be echoed then you should do:

if(a === x)
{
    echo "a";
}else
{
    die();
}

if(b === y)
{
    echo "b";
}

if(c === z)
{
    echo "c";
}

But I want to make sure that if one of the 3( a,b,c ) doesn't equal the corresponding 3(x,y,z) nothing is echoed.

---

I also can't use:

if (a == x && b == y && c == z) {
    echo "success";
}

as each hypothetical condition is huge (ie a database insert and checking whether a url is working etc...)

With an example of checking whether a url is working:

$file_headers = @get_headers("https://www.google.co.uk/");
if($file_headers[0] == 'HTTP/1.1 404 Not Found') {

}
else {
    echo "Success concerning url";
}

and an example of inserting into a database:

if($result)
{
    echo "Success concerning inserting information to the database";
}

Is there a method on how to do this?

Answer 1

Whats the context of this? Anyway, just put them inside all together:

if($a === 'x' && $b === 'y' && $c === 'z') {
    // satisfied all three conditions, then proceed
} else {
    // if one of them fails, stop the process
}

Answer 2

Introducing boolean operators: and ( && ) and or ( || ).

if(a === x && b === y && c === y) {
    echo "a";
    echo "b";
    echo "c";
} else {
    die();
}

Similarly, you could kill the script if any of the conditions are not true.

if(a !== x || b !== y || c !== z) {
    die();
}

echo "a";
echo "b";
echo "c";

---

If you have many booleans ( a === x ) that make your conditional super long and difficult to read, you can always set the booleans to variables:

$boolA = a === x;
$boolB = b === y;
$boolC = c === y;
$boolZ = z < 0 || z >= 100 || z === (a + b + c);

if(!$boolA || !$boolB || !$boolC || !$boolZ) {
    die();
}

// success

You could also make one or many functions to potentially clean up your code:

function isValid() {
    // perform lots of logic
    return true;
}

if(!isValid()) die();

// success

---

In the end of the day..the more complex your code gets, the more you should be using OOP . There are a lot of PHP frameworks that will help a beginner get started in this mindset.

Since I've been using Laravel recently, I'll use them as an example. First you have a routing file, which takes all requests to your site and dispatches them to certain classes & methods.

// Create a filter for checking if a URL is working
Route::filter('urlCheck', function()
{
    $file_headers = @get_headers("https://www.google.co.uk/");
    if($file_headers[0] == 'HTTP/1.1 404 Not Found') {
        // return a 404 page
    }

    // continue with the normal response
});

// Create a route for a basic request to http://example.com/test
Route::get('test', array('before' => 'urlCheck', function() {
    // create page for successful request to GET /test
}));

Answer 3

But I want to make sure that if one of the 3(a,b,c) doesn't equal the corresponding 3(x,y,z) nothing is echoed.

is fulfilled by this:

if (a == x && b == y && c == z) {
    echo "all match";
}