Php-mysql Course

PHP has both integer and float (decimal) number types. These two types can be classified under the generic title numbers.
Valid numbers can be anything like:   8,   258,   -37,   89.25,   -3.5785,   5.5e2
- Number-type values are never quoted. The numbers added within quotes are strings with numeric values.
PHP supports a maximum integer of around two billion on most platforms (UNIX and Windows). With numbers larger than that, PHP will automatically use a floating-point type.

1. Numbers and Operator

The mathematical operators are specific symbols that performs mathematical calculations.
Operators act on the variables and numbers presented in PHP instructions.

The standard mathematical (Arithmetic) operators


Assignment Operators


The mathematical calculations in PHP, as in arithmetic, are taken into account the operators precedence (the order in which complex calculations are made). If you want to force the execution order, you must group clauses in parentheses. Check the fallowing example:
<?php
$x = 8 + 3 * 5 -2;
echo $x;                  // 21 (first 3*5 [15], then adds 8 and substract 2 )

$x = (8+3) * (5-2);
echo '<br />'. $x;        // 33  (first 8+3  [11], then  5-2 [3], then makes the multiplication  11*3 [33] )
?>

2. PHP mathematical functions

Along with the arithmetic operators you can use PHP mathematical functions for more complex operations.
Here are some examples of functions:

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which attribute is used in <a> tag for the address of the link?
src href rel
<a href="http://coursesweb.net/" title="CoursesWeb.net">CoursesWeb.net</a>
Which CSS property sets the type of the text font?
font-family text-decoration font-size
h2 {
  font-family:"Calibri",sans-serif;
}
What instruction selects all the <div> tags with class="cls"?
querySelector("div.cls") getElementsByTagName("div") querySelectorAll("div.cls")
var elm_list = document.querySelectorAll("div.cls");
var nr_elms = elm_list.length;       // number of selected items
alert(nr_elms);
Indicate the function that can be used to get the sum of values in an array.
array_sum() array_diff() array_shift()
$arr =[1, 2, 3, 4);
$arr_sum = array_sum($arr);
echo $arr_sum;       // 10
Numbers and mathematical 0perators

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