PHP ??? ??? (?? ???)

PHP 7 ?? ?? ? ??? ??? (?? ???)? ? ?? ???? ???? ? ?????. $b?? ??? ??? ?? ?? -1, 0 ?? 1? ?????. Example

<?php
// 整型比較
print( 1 <=> 1);echo "<br/>";
print( 1 <=> 2);echo "<br/>";
print( 2 <=> 1);echo "<br/>";
print(PHP_EOL);
// 浮點型比較
print( 1.5 <=> 1.5);echo "<br/>";
print( 1.5 <=> 2.5);echo "<br/>";
print( 2.5 <=> 1.5);echo "<br/>";
print(PHP_EOL);
// 字符串比較
print( "a" <=> "a");echo "<br/>";
print( "a" <=> "b");echo "<br/>";
print( "b" <=> "a");echo "<br/>";
?>
? ???? ??? ?? ??? ??? ????. 0-110-1

1

0

-1

1





???? ??
||
<?php // 整型比較 print( 1 <=> 1);echo "<br/>"; print( 1 <=> 2);echo "<br/>"; print( 2 <=> 1);echo "<br/>"; print(PHP_EOL); // 浮點型比較 print( 1.5 <=> 1.5);echo "<br/>"; print( 1.5 <=> 2.5);echo "<br/>"; print( 2.5 <=> 1.5);echo "<br/>"; print(PHP_EOL); // 字符串比較 print( "a" <=> "a");echo "<br/>"; print( "a" <=> "b");echo "<br/>"; print( "b" <=> "a");echo "<br/>"; ?>