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From: http://www.faqts.com/knowledge_base/view.phtml/aid/1/fid/40
1.
Speed. There is a difference between the two, but speed-wise it should be irrelevant which one you use. echo is marginally faster since it doesn't set a return value if you really want to get down to the nitty gritty.
2.
Expression. print() behaves like a function in that you can do: $ret = print "Hello World"; And $ret will be 1. That means that print can be used as part of a more complex expression where echo cannot. An example from the PHP Manual:
$b ? print "true" : print "false";
print is also part of the precedence table which it needs to be if it is to be used within a complex expression. It is just about at the bottom of the precedence list though. Only "," AND, OR and XOR are lower.
- Parameter(s). The grammar is: echo expression [, expression[, expression] ... ] But echo ( expression, expression ) is not valid. This would be valid: echo ("howdy"),("partner"); the same as: echo "howdy","partner"; (Putting the brackets in that simple example serves no purpose since there is no operator precedence issue with a single term like that.)
So, echo without parentheses can take multiple parameters, which get concatenated:
echo "and a ", 1, 2, 3; // comma-separated without parentheses
echo ("and a 123"); // just one parameter with parentheses
print() can only take one parameter:
print ("and a 123");
print "and a 123";