为什么打印和回声在“for”循环中表现不同[重复]

Question

This question already has an answer here:

• How are echo and print different in PHP? [duplicate] 5 answers

If I use print in this code:

<?php
for($i = 1; $i <= 3; print $i . "
") {
  $i++; 
}   
?>

I see as output this:

2

3

4

But when I use echo the code doesn't work:

<?php
for($i = 1; $i <= 3; echo $i . "
") {
  $i++; 
}   
?>

I see this error:

PHP Parse error: syntax error, unexpected 'echo' (T_ECHO), expecting ')' in /media/datos/xampp/htdocs/temp/1.php on line 3

My question is:

• Why can I use print as a third expression in a for loop, but cannot when using echo and why do they behave differently from each other?

References:

• http://php.net/echo
• http://php.net/print

</div>

Answer 1

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";

Some part of my answer are part of below answer. I think this is the answer of your question. Most important part is print() behaves like a function

see this answer: https://stackoverflow.com/a/234255/1848929

What about echo:

Note: Because this is a language construct and not a function, it cannot be called using variable functions.

see notes part on this page: http://us2.php.net/manual/en/function.echo.php