How does the use of variables impact the decision between echo and printf for outputting strings in PHP?

When using variables in PHP, the decision between using echo and printf for outputting strings depends on whether you need to format the string with specific placeholders for variables. If you need to include variables within the string and format it, printf is the better choice as it allows for placeholders like %s for strings and %d for integers. If you simply need to output a string without any formatting, echo is a simpler and more straightforward option.

// Using echo to output a string with a variable
$name = "John";
echo "Hello, $name!";

// Using printf to format a string with a variable
$name = "Jane";
printf("Hello, %s!", $name);