超越PHP - Exceed PHP: is_bool

描述

bool is_bool ( mixed var)

如果 var 是 boolean 则返回 TRUE。

例子 1. is_bool() 示例

<?php $a = false; $b = 0; // 因为 $a 是布尔型，所以结果为真 if (is_bool($a)) { print "Yes, this is a boolean"; } // 因为 $b 不是布尔型，所以结果为非真 if (is_bool($b)) { print "Yes, this is a boolean"; } ?>

参见 is_array()、is_float()、is_int()、is_integer()、is_string() 和 is_object()。

add a note User Contributed Notes
is_bool

jeppe at bundsgaard dot net
08-Nov-2003 06:05

This outputs the textvalue of a boolean.

echo "$boolean is:
".($boolean ? "true":"false");

daevid at daevid dot com
08-Jul-2003 03:12

Because PHP annoyingly doesn't convert booleans to any sort of printable
value when you echo or print them, use a little function like
this:

function printArray($myArray)
{
	reset
($myArray);	
	while (list ($key, $val) = each ($myArray)) 
	{
		if
(is_bool($val)) $val = ($val) ? "true" :
"false";
		echo "[$key] =>
$val
\n";
	}
}

miguel at lugopolis dot net
13-Jun-2003 04:11

This is a simple test to see how is_null() evaluates diferent datatypes.
This test can be used to see how the is_* functions evaluates for each data
types.
$vars=array("NULL"=>NULL, // evaluates as Not
boolean
            "TRUE"=>TRUE, // evaluates as
Boolean
            "FALSE"=>FALSE, // evaluates as
Boolean
            "STRING"=>"", // evaluates as
Not boolean
            "INTEGER"=>0, // evaluates as Not
boolean
            "FLOAT"=>0.0, // evaluates as Not
boolean
            "ARRAY"=>array(), // evaluates as Not
boolean
            "OBJECT"=> new stdClass(), // evaluates
as Not boolean
            );

foreach ($vars as $type=>$value)
{
   if (is_bool($value)) {
      echo "$type is
bool\n";
   } else {
      echo "$type is NOT
bool\n";
   }
}

joeldg at tenshimedia.com
09-Oct-2002 06:09

# basic fuzzy logic..
# extends out our boolean logic
further...
#
#	truth(not x) = 1.0 - truth(x)
#	truth(x and y) =
minimum (truth(x), truth(y))
#	truth(x or y) = maximum (truth(x),
truth(y))
# uncomment below to test.
/*
$fz1 = 0.5;	// 0.5
start
$fz2 = fuzz(fuzz($fz1, 0.4, "&") , fuzz(0.45,
"", "|"), "&");// 0.45
$fz3 =
fuzz(fuzz($fz2, $fz2, "!"), $fz2, "|");// 0.55
$fz4
= fuzz(fuzz($fz1, $fz1, "!"), $fz2, "-"); 	//
0.95
$bl5 = fuzz ($fz3, $fz2); // false
$bl6 = fuzz ($fz2, $fz3);//
true

echo "fz1 = " .$fz1 . "
";
echo
"fz2 = " .$fz2 . "
";
echo "fz3 = "
.$fz3 . "
";
echo "fz4 = " .$fz4 .
"
";
echo "bl5 = " . (($bl5) ? "true" :
"false") ."
";
echo "bl6 = " . (($bl6)
? "true" : "false");
*/

function fuzmin($a,
$b){
	return (($a < $b) ? $a : $b); 
}// end function
function
fuzmax($a, $b){
	return (($a > $b) ? $a : $b); 
}// end
function

function fuzz($a, $b=0, $op=""){
	switch
($op){
		case "|":
			return ($a > $b) ? $a : $b;

			break;
			
		case "&":
			return ($a < $b)
? $a : $b; 
			break;
		case "!":
			return 1 -
$a;
			break;
		case "+":
			return
$a+$b;
			break;
		case "-":
			return $a-$b;
		case
"*":
			return $a*$b;
		case "/":
			return
$a/$b;
		
		default :
			return ($a <=
$b);
	}//case
}//function

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