String is a series of characters. We can wrap a string in single quotes or double quotes.
$x = "Hello";
echo $x; // Hello
However, we can only use variables in double-quote, not single-quote.
$firstName = "Dev";
echo 'Hello $firstName'; // Hello $firstName
echo "Hello $firstName"; // Hello Dev
In PHP, we can join strings together using dot . operator.
$x = "Hello";
$y = "World";
$c = $x." ".$y;
We can use the backslash \ as an “escape” character. \n doesn’t work inside of a single-quoted string.
echo "Hello. \"This string's in double quotes.\" ";
// Hello. "This string's in double quotes."
We can use a zero-based index to access a letter in a string.
The first letter is in a 0 position. A minus position is counted from the end of a string.
$x = "Hello World";
echo $x[1]; // e
echo $x[-3]; // r
We can also change a letter in a string by using bracket the same way.
$x = "Hello World";
$x[4] = "y";
echo $x; // Helly World
We can use also use heredoc and nowdoc to declare a string.
They help improving the readability of the code.
PHP heredoc strings are like double-quoted strings, without the double-quotes. So they don’t need to escape quotes and expand variables.
We can start with the <<< operator and an identifier.
$str = <<<TEXT
a string
can span multiple lines
and include single quote ' and double quotes "
TEXT;
Example:
<?php
$x = "a";
$y = "b";
$z = "c";
echo <<<TEXT
Line 1 $x
Line 2 $y
Line 3 $z
TEXT;
// Line 1 a Line 2 b Line 3 c
nowdoc is similar to single-quoted string, so we can’t use variables inside nowdoc.
<?php
$name = "Dev";
echo <<<'TEXT'
My name is "$name". I am going $a->b.
TEXT;
// My name is "$name". I am going $a->b.