In PHP, strings are sequences of characters, each of which corresponds to a single byte. This means that PHP does not support Unicode by default, and to work with multilingual strings, such as Cyrillic, you need to use special functions designed for multibyte encodings. The easiest way to create a string is to enclose it in quotation marks. Single quotation marks interpret everything literally, including special characters such as \n, while double quotation marks allow you to use control characters and variable substitution.
One of the most common operations with strings in PHP is combining several strings into one. This is called concatenation and is performed using the .. operator. In addition, there is a shortened version that allows you to add content to an existing string — it is especially useful when strings are formed inside loops, for example, when building page headers based on filters. If strings are stored in an array, they can be “glued” together sequentially by iterating through the array and adding each string to a common variable.
When analyzing strings, it is often necessary to determine their length. The usual function counts the number of bytes, not characters. Therefore, if the string contains Cyrillic characters, it is better to use a function that works with UTF-8 to get the actual number of characters. You can also find out the length of the string without spaces. To do this, first remove all spaces, and then count the length of the remaining text.
In PHP, you can determine how many words a string contains. By default, this operation only works with Latin characters, so for Russian, you have to specify a list of valid characters manually and then count the number of elements in the resulting array of words. If desired, you can also determine the number of spaces, line breaks, punctuation marks, numbers, and letters. All these operations are performed using functions that count the occurrences of a substring or regular expressions.
Searching for information in strings includes determining the number of occurrences of a specific word, the position of its first or last occurrence, and obtaining all the positions where it occurs. This is especially important when you need to replace all occurrences or only some of them. It is important to take into account the case of characters, because most functions distinguish between, for example, “Text” and “text”.
To modify strings, you can replace individual characters or substrings. For example, you can replace the word “green” with “red” in a long sentence. If the string is encoded in UTF-8, special functions are used for accurate slicing and replacement to avoid errors when trimming multilingual strings.
PHP also provides a simple way to replace characters in an entire string. This can be useful, for example, to replace spaces with underscores when generating URLs. In addition, you can change a string up to a certain character — for example, overwrite everything before a semicolon.
All these features allow you to flexibly manage text in web applications: create dynamic headers, process user input, filter out unwanted fragments, generate descriptions, and adapt content to the needs of the project. Working with strings is a fundamental skill for any PHP developer.