Labs

In this episode, we’ll take on the challenge of how to test a string to see if it starts with “http://”. You’ll discover there are multiple ways to do this check. Then we’ll create a utility function called starts_with and put that into our new Site Utilities plugin. Regex is not needed here. In this episode, I show you two different approaches to checking if a string begins with a substring: Check its position using strpos Check the beginning of the string to a specific length using mb_substr and mb_strlen

There are times when you need to know the length of a string. For example, if you are checking for a string and you want to know if it’s at the end of another string, then you need to know the length of what you are looking for first. That’s a good example. Let’s get you started learning about string lengths, how it’s processed (character vs. byte count), and character encoding. In this episode, you’ll work with the PHP instruction strlen. This instruction counts the number of bytes in the string, not the number of characters. For now, don’t worry […]

In the last episode, you checked if a substring is present in the subject string. In this one, let’s replace it with another substring if it is.

Often we need to build strings incrementally. A good example is with building an output HTML string pattern or even a message. You build part of it, do some processing, and then keep appending to the same string and assigning it back to the variable. PHP gives you a shortcode operator for this process that turns: $message = $message . ‘Welcome ‘ . $first_name; into: $message .= ‘Welcome ‘ . $first_name;. Both of these lines of code are processed the same way by the PHP interpreter. First, the strings are concatenated. Then the assignment is made to the variable $message.

PHP provides the means for us to build dynamic strings, i.e. strings that have varying strings within them. One method is to embed a variable directly into the string. When PHP comes to a single quote, it handles the string within the quotes as a string literal. There is no processing that happens. Rather, it treats it as a hard-coded string. Therefore, if you wrote echo ‘My name is {$first_name}.’, the entire string would be rendered out to the browser just as you wrote it. The variable would not be processed.