Why Does Echoing with Commas Work While Returning with Commas Doesn't?

When concatenating values using echo and return in PHP, there is a subtle difference between using periods and commas. Specifically:

• Echo: Allows multiple expressions separated by commas to be echoed to the output.
• Return: Can only return a single expression.

Using Periods

The period (.) operator concatenates strings or other data types into a single string. For example:

echo $value . ' continue'; // Outputs: $value continue
return $value . ' continue'; // Also outputs: $value continue

Using Commas

Within an echo statement, a comma separates multiple expressions that are to be echoed to the output. For example:

echo $value, ' continue'; // Outputs: $value continue

However, using commas within a return statement is not valid syntax. This is because return only allows one expression as its return value.

return $value, ' continue'; // Causes an error

Conclusion

Remember that echo operates differently from return. Echo accepts multiple expressions separated by commas, while return only allows a single expression. Therefore, when concatenating values, use a period if you want to return a single string or a period and commas if you want to echo multiple expressions.