Well Golly

As I mentioned in the previous posts, I’m using W3Schools to review HTML, CSS, and PHP in order to create some exercises. Here are a few things that I didn’t know about PHP or want to remind myself about.

When sending users to specific pages I often use numbers to indicate which page they should go to. Spambots will frequently put in random junk so I do some tests before I process the request. PHP has some odd behaviour with some of the functions. For example,

// Invalid calculation will return a NaN value
$x = acos(8);
echo is_nan($x);     --> 1
echo var_dump($x);   --> float(NAN)
echo is_null($x);    --> expect 0 but get a blank line, so only works on numbers—not NAN
echo is_finite($x);  --> blank line, so only works on numbers—not NAN

echo is_finite("Hello");     --> Warning: is_finite() expects parameter to be a float
echo is_finite(10);          --> 1
echo is_infinite(10);        --> expect 0 but get a blank line
echo is_infinite(10e1111);   --> 1

// $hello not defined
echo var_dump($hello);       --> NULL
echo is_nan($hello);         --> blank line
echo is_null($hello);        --> 1
echo is_finite($hello);      --> 1
echo is_infinite($hello);    --> expect 0 but get a blank line
echo is_int($hello);         --> expect 0 but get a blank line

var_dump(is_numeric($hello)); --> bool(true) 
is_numeric($hello);           --> expect 0 but get a blank line

I never gave constants much thought when developing web pages, but i’m thinking that they might come in handy when making interactive games. If I access the database and grab a bunch of data that will be displayed but won’t change, it should go into a constant array which is then accessible to any function on the page. Note that both constant arrays and variables are referenced by their name without a $ before the name.

define("cars", [
    "Alfa Romeo",
    "BMW",
    "Toyota"
]);
echo cars[0];  --> Alfa Romeo

function arrayDisplay() {
  foreach (cars as $value) {
        echo "$value ";
    }
}
arrayDisplay();  --> Alfa Romeo BMW Toyota

If you use a variable array, the array isn’t available to functions.

$cars = array(
    "Alfa Romeo",
    "BMW",
    "Toyota"
);
var_dump($cars);  -->  array(3) { [0]=> string(10) "Alfa Romeo" [1]=> string(3) "BMW" [2]=> string(6) "Toyota" }

function arrayDisplay() {
  foreach ($cars as $value) {
        echo "$value ";
    }
}
arrayDisplay(); -- > Warning: Invalid argument supplied for foreach() … 

As I mentioned in the previous post, I’m using W3Schools to review HTML and CSS in order to create some exercises. Here are a few things that I didn’t know about CSS or want to remind myself about.

“Note: Remember that the height and width properties do not include padding, borders, or margins! They set the height/width of the area inside the padding, border, and margin of the element!”

Padding (outline, margins, and border) in CSS is added to the width of an element. So div { width: 300px; padding: 25px;} will have a width of 325 pixels. To keep the width at 300 px you need to add the declaration box-sizing: border-box; inside the brackets.

Occasionally I want to add whitespace and end up using   a bunch of times. There is a descriptor, white-space: pre; that will work.

This is a paragraph that has a bunch of spaces before the last word.

There are a bunch of ways to control elements based on where they appear in relation to other elements. I haven’t made much use of these selectors, but mostly because I’m not familiar with them. You can explore them at this W3Schools page.

The column-count:n property is something I wish I had known about. It can be used to divide a div (or p) into columns.

Here’s another property that can come in handy in association with justify, margin-right: 20%; -webkit-hyphens: auto; -ms-hyphens: hyphens: auto. You need all three to handle different browsers.

I just learned about display: flex; justify-content: center; when laying out the previous two paragraphs. I first put them in a div and did a float: left and float:right to get them to display next to each other. Then I manipulated the margins to get them closer to the center. This works better and I just need to make sure there is enough padding so that they don’t brush up against each other.