PHP comparison operator

Comparison Operators

Example	Name	Result
$ A = $ B	Equal	TrueIf$Is equal$ B.
$ A ===$ B	Identical	TrueIf$Is equal$ B, And they are of the same type. (introduced in PHP 4)
$! = $ B	Not equal	TrueIf$Is not equal$ B.
$ A <> $ B	Not equal	TrueIf$Is not equal$ B.
$! ==$ B	Not identical	TrueIf$Is not equal$ B, Or they are not of the same type. (introduced in PHP 4)
$ A <$ B	Less	TrueIf$Is strictly less$ B.
$ A> $ B	Greater	TrueIf$Is strictly greater$ B.
$ A <= $ B	Less than or equal	TrueIf$Is less than or equal$ B.
$ A> = $ B	Greater than or equal	TrueIf$Is greater than or equal$ B.

 

Note: If you compare a string with an integer value. String is converted to the number type (integer or float type), and then compared with integer.

 

  1   <?  PHP
  2      Var_dump  (  0     =     "  A  "  ); //  0 = 0-> true  
  3      Var_dump  (  "  1  "     =     "  01  "  );  // 1 = 1-> true  
  4     Var_dump  (  "  1  "     =     "  1e0  "  );  //  1 = 1-> true 
  5     
  6     Switch  (  "  A  "  ){
  7     Case     0  : 
  8     Echo     "  0  "  ;
  9     Break  ;
  10     Case     " A  "  :     //  Never reached because "A" is already matched with 0  
  11       Echo     "  A  "  ;
  12    Break  ;
  13   }
  14     ?>   
  15    

 

 

COMPARISON WITH VARIOUS TYPES

Type of operand 1	Type of operand 2	Result
Null or string	String	ConvertNullTo "", numerical or lexical comparison
Bool or null	Anything	Convert to bool,False<True
Object	Object	Built-in classes can define its own comparison, different classes are uncomparable, same class-compare properties the same way as arrays (PHP 4), PHP 5 has its own explanation
String, resource or number	String, resource or number	Translate strings and resources to numbers, usual math
Array	Array	Array with fewer members is smaller, if key from operand 1 is not found in operand 2 then arrays are uncomparable, otherwise-compare value by value (see following example)
Array	Anything	Array is always greater
Object	Anything	Object is always greater

 

When comparing two numbers, we 'd better understand all the meanings in this table first. Yes.

I once suffered losses here.

 

In addition, when comparing two values, if you can use "=" and "! The = "operator uses the two operators. This prevents PHP from automatically converting data types.