Difference between period and comma when concatena

Question

I just found that this will work:

echo $value , " contiue";

but this does not:

return $value , " contiue";

While "." Works in both.

What is the difference between a period and a comma here?

Answer 1

You also have to note that echo as a construct is faster with commas than it is with dots.

So if you join a character 4 million times this is what you get:

echo $str1, $str2, $str3;

About 2.08 seconds

echo $str1 . $str2 . $str3;

About 3.48 seconds

This is because PHP with dots joins the string first and then outputs them, while with commas just prints them out one after the other.

Source

Answer 2

echo is a language construct (not a function) and can take multiple arguments, that's why , works. using comma will be slightly even (but only some nanoseconds, nothing to worry about)

. is the concatenation operator (the glue) for strings

Answer 3

Dot (.) is for concatenation of a variable or string. This is why it works when you echo while concatenating two string and it works when you return a concatenation of a string in a method. But the comma doesn't concatenate and this is why the return statement won't work.

echo is a language construct that can take multiple expressions which is why the comma works:

void echo ( string $arg1  [, string $...  ] )

Use the dot for concatenation

Answer 4

the . is the concatenation operator in PHP, for putting two strings together. The comma can be used for multiple inputs to echo.

Answer 5

echo is actually a function (not really but let's say it is for argument) that takes any number of parameters and will concatenate them together.

While return is not a function, but rather a keyword, that tells the function to return the value, and it is trying to interpret , as some kind of operator. You should be using . as the concatenation operator in the case when you are using the return statement.

Answer 6

return does only allow one single expression. But echo allows a list of expressions where each expression is separated by a comma. But note that since echo is not a function but a special language construct, wrapping the expression list in parenthesis is illegal.