How Do Curly Braces {} Work in PHP String Interpolation?

Curly Braces in String Literals in PHP

Question: What do the curly braces { } represent when used within string literals in PHP?

Answer:

Curly braces in string literals in PHP indicate the use of "complex (curly) syntax" for string interpolation. This syntax enables the inclusion of expressions within strings.

According to the PHP documentation, any scalar variable, array element, or object property with a string representation can be added to a string using this syntax. To do so, simply enclose the expression within curly braces { }.

It's important to note that the { cannot be escaped, so the syntax is only recognized when the $ immediately follows the {. To obtain a literal {$, use $.

Here are some examples to illustrate the usage:

$great = 'fantastic';

// Won't work, outputs: This is { fantastic}
echo "This is { $great}";

// Works, outputs: This is fantastic
echo "This is {$great}";
echo "This is ${great}";

The complex syntax is especially useful when expressions are complex or require accessing multi-dimensional arrays or object properties:

echo "This is the value of the var named $name: {${$name}}";

echo "This is the value of the var named by the return value of getName(): {${getName()}}";

echo "This is the value of the var named by the return value of $object->getName(): {${$object->getName()}}";

While curly braces are often not necessary, they are required in situations where the variable name is not immediately recognizable, such as "$aefgh" in the following example:

$out = "$aefgh";

To resolve this, curly braces can be used to explicitly specify the variable name:

$out = "${a}efgh"; // or
$out = "{$a}efgh";

The above is the detailed content of How Do Curly Braces {} Work in PHP String Interpolation?. For more information, please follow other related articles on the PHP Chinese website!