How to use the combined comparison operator (<=>) in PHP7? (code example)

The combined comparison operator () is a very useful operator. This article will show you how to use the combined comparison operator (). I hope it will be useful to you. help.

Combined comparison operator ()

## operation operator is a three-way comparison operator that performs greater than, less than, and equality comparisons between two operands. [Video tutorial recommendation:

PHP tutorial]

Example:

$c = $a <=> $b;
// 这相当于
$c = ($a < $b) ? -1 : (($a > $b) ? 1 : 0);

Explanation: The operator behaves like strcmp( ) or version_compare(); it can be used with integers, floats, strings, arrays, objects, etc.

The combined comparison provided by the operator:

● If the values ​​on both sides are equal, 0 is returned

● If the left If the value on the right side is greater, return 1

● If the value on the right side is greater, return -1

Code example

Let’s use code examples to see how the operator performs combined comparisons.

Example 1: Integer comparison

<?php 
echo"整数 <br>"; 
echo 7 <=> 7 ; 
echo"<br>"; 
echo 7 <=> 6; 
echo"<br>"; 
echo 6 <=> 7; 
?>

Rendering:

Example 2: Floating point number Comparison

<?php 
echo"浮点数<br>"; 
  
echo 2.5 <=> 1.5;  
echo"<br>"; 
echo 0.5 <=> 1.5;  
echo"<br>"; 
echo 1.5 <=> 1.5;  
?>

Rendering:

Example 3: String comparison

<?php 
echo"<br>字符串<br>"; 
echo "a" <=> "a" ; 
echo"<br>"; 
echo "g" <=> "b" ;  
echo"<br>"; 
echo "a" <=> "b" ;  
echo"<br>"; 
echo "A" <=> "B" ;  
echo"<br>"; 
echo "a" <=> "B" ;  
echo"<br>"; 
echo "2" <=> "1" ;  
echo"<br>"; 
echo "2" <=> "a" ;  
echo"<br>"; 
echo "2" <=> "A" ;  
?>

Rendering ：

Description: String comparison size, the comparison is the value of ascii code. The following are the ascii codes corresponding to some characters

● “0”~”9”: 48~57

● “A”~“Z”: 65~90

● “a”~”z”: 97~122

Example 4: Array comparison

<?php 
echo"<br>数组<br>"; 
echo [] <=> [];  
echo"<br>"; 
echo [1, 7, 3] <=> [1, 7, 3]; 
echo"<br>"; 
echo [1, 7, 3, 5] <=> [1, 7, 3]; 
echo"<br>"; 
echo [1, 7, 3] <=> [4, 4, 4]; 
echo"<br>"; 
?>

Rendering:

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