I read somewehere (I thought on codinghorror) that it is bad practice to add strings together as if they are numbers, since like numbers, strings cannot be changed. Thus, adding them together creates a new string. So, I was wondering, what is the best way to add two strings together, when focusing on performance?
Which of these four is better, or is there another way which is better?
//Note that normally at least one of these two strings is variable $str1 = 'Hello '; $str2 = 'World!'; $output1 = $str1.$str2; //This is said to be bad $str1 = 'Hello '; $output2 = $str1.'World!'; //Also bad $str1 = 'Hello'; $str2 = 'World!'; $output3 = sprintf('%s %s', $str1, $str2); //Good? //This last one is probaply more common as: //$output = sprintf('%s %s', 'Hello', 'World!'); $str1 = 'Hello '; $str2 = '{a}World!'; $output4 = str_replace('{a}', $str1, $str2); Does it even matter?
You are always going to create a new string whe concatenating two or more strings together. This is not necessarily ‘bad’, but it can have performance implications in certain scenarios (like thousands/millions of concatenations in a tight loop). I am not a PHP guy, so I can’t give you any advice on the semantics of the different ways of concatenating strings, but for a single string concatenation (or just a few), just make it readable. You are not going to see a performance hit from a low number of them.