Concatenate PHP function output to a string like variables

Question

For variable $x we can concatenate it to a string in many ways, one of them is like the following:

$x = "Hello";
echo "I say {$x} to all of you.";
// The output should be: I say Hello to all of you.

However, If I tried to do something like this with a function, it will fail:

$x = "Hello";
echo "I say {strtolower($x)} to all of you.";
// The output should be: I say {strtolower(Hello)} to all of you.

If there is a synonym way just like used for the variable, I will be appreciated to know it. In other words, I don't want to split the main string and I don't want to use sprinf.

Answer 1

You can concatenate with . operator:

echo "I say  " . strtolower($x) . " to all of you.";

Or just :

echo "I say  ", strtolower($x), " to all of you.";