PHP: Extracting characters from string
Sometimes we need to get one character from a string. For example, if a website stores user's name and last name, and at some moment we need to display this infomation in the abbreviated format, like
A. Ivanov, we would need to extract the first character of the user's name.
<?php $firstName = 'Alexander'; print_r($firstName); // => A
The square braces with a number in it - is a special operator used to extract a character from a string. The number inside is called an index or an offset - the character position inside the string. In almost all programming languages, the index numeration starts from 0. Therefore, we can access the first character by referring to it with the
PHP also supports negative string offsets. In that case, we refer to characters from the end of the string.
-1 is the index of the last character,
-2 is refers to the second last character and so on. Unlike the zero-based forward offsets, in case of inverted offset the first character's index is
<?php $firstName = 'Alexander'; print_r($firstName[-1]); // => r
An index can be represented not only by a number, but also by a variable value. The following example will produce the same result - the output of the character
A, even though it's index inside the square brackets is specified by a variable, rather than a specific number.
<?php $firstName = 'Alexander'; $index = 0; print_r($firstName[$index]); // => A
You have three variables with last names of three different persons. Combine the characters and print them to screen in the following order:
- the third character from the first string;
- the second character from the second string;
- the forth character from the third string;
- the fifth character from the second string;
- the third character from the second string.
Try using interpolation: in addition to usual variables, you can put inside curly braces variables with an index in square brackets that refers to a separate character