http://www.php.net/manual/en/class.mysqli-stmt.php What does void mean?

You will notice that for prepared statements, the php.net list of functions is available at http://www.php.net/manual/en/class.mysqli-stmt.php even functio开发者_StackOverflowns such as -> execute(); have the word void next to them what does this mean?

As I use many of these in my scripts, is it safe to do so?

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Void just means nothing is returned when the method has finished executing.

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void means "nothing" (in the meaning of the word). In PHP its equivalent to null. Usually you describe a return value with void, if the return expression in the method is completely omitted, whereas null as return value usually means

return null;

Note, that void is a pseudo-type in PHP. It doesnt exists in PHP and its only used in documetation to tell you, that there is really nothing (useful) returned.

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From the PHP Manual on Pseudo-Types and Variables:

void as a return type means that the return value is useless. void in a parameter list means that the function doesn't accept any parameters.

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Just like bool and int, void is a type. Placed beside a function declaration's name, it signifies that the function does not return anything. However, that does not mean the function does not perform any operations; it may have side effects, or it may execute other commands without passing anything back to the receiver.