Why Can Commas Be Used for Echoing but Not for Returning in PHP?

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:

<code class="php">echo $value . ' continue'; // Outputs: $value continue
return $value . ' continue'; // Also outputs: $value continue</code>

Using Commas

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

<code class="php">echo $value, ' continue'; // Outputs: $value continue</code>

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

<code class="php">return $value, ' continue'; // Causes an error</code>

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.

The above is the detailed content of Why Can Commas Be Used for Echoing but Not for Returning in PHP?. For more information, please follow other related articles on the PHP Chinese website!