PHP 中的 echo 和 print 有何不同？

How are echo and print different in PHP?

提问by zuk1

Possible Duplicate:
Reference: Comparing PHP's print and echo

可能的重复：
参考：比较 PHP 的打印和回显

Is there any major and fundamental difference between these two functions in PHP?

PHP 中的这两个函数之间有什么主要和根本的区别吗？

回答by dl__

From: http://web.archive.org/web/20090221144611/http://faqts.com/knowledge_base/view.phtml/aid/1/fid/40

来自：http: //web.archive.org/web/20090221144611/http: //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 $retwill 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:

1. 速度。两者之间存在差异，但速度方面应该与您使用哪一个无关。echo 稍微快一点，因为如果您真的想深入了解它，它不会设置返回值。

2. 表达。print()行为就像在你可以做一个函数： $ret = print "Hello World"; 并且$ret会1。这意味着 print 可以用作更复杂的表达式的一部分，而 echo 不能。PHP手册中的一个例子：

$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 ,ANDORXORare lower.

print 也是优先级表的一部分，如果要在复杂的表达式中使用它，它需要是优先级表的一部分。不过，它位于优先级列表的底部。只有,ANDORXOR更低。

1. 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.)

3. 参数）。语法是：echo expression [, expression[, expression] ... ]但echo ( expression, expression )无效。这将是有效的：echo ("howdy"),("partner"); 一样：echo "howdy","partner"; （把括号放在那个简单的例子中是没有意义的，因为像这样的单个术语没有运算符优先级问题。）

So, echo without parentheses can take multiple parameters, which get concatenated:

因此，没有括号的 echo 可以采用多个参数，这些参数会被连接起来：

   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()只能带一个参数：

   print ("and a 123");
   print  "and a 123";

回答by seanyboy

They are:

他们是：

• print only takes one parameter, while echo can have multiple parameters.
• print returns a value (1), so can be used as an expression.
• echo is slightly faster.

• print 只需要一个参数，而 echo 可以有多个参数。
• print 返回值 (1)，因此可以用作表达式。
• echo 稍微快一点。

回答by seanyboy

To add to the answers above, while print can only take one parameter, it will allow for concatenation of multiple values, ie:

添加到上面的答案中，虽然 print 只能采用一个参数，但它允许连接多个值，即：

$count = 5;

print "This is " . $count . " values in " . $count/5 . " parameter";

This is 5 values in 1 parameter

这是 1 个参数中的 5 个值

回答by grilix

I think print()is slower than echo.

我认为print()比echo.

I like to use print()only for situations like:

我喜欢print()仅用于以下情况：

 echo 'Doing some stuff... ';
 foo() and print("ok.\n") or print("error: " . getError() . ".\n");

回答by Ross

As the PHP.net manual suggests, take a read of this discussion.

正如 PHP.net 手册所建议的，请阅读此讨论。

One major difference is that echocan take multiple parameters to output. E.g.:

一个主要区别是echo可以带多个参数输出。例如：

echo 'foo', 'bar';   // Concatenates the 2 strings
print('foo', 'bar'); // Fatal error

If you're looking to evaluate the outcome of an output statement (as below) use print. If not, use echo.

如果您要评估输出语句的结果（如下所示），请使用print. 如果没有，请使用echo.

$res = print('test');
var_dump($res); //bool(true)