PHP Cast Int to Boolean: Step-by-Step Guide and Best Practices
Learn how to convert integers, strings, and other data types to boolean in PHP with our step-by-step guide and best practices. Negate an integer twice or use (bool) or (boolean) casts for strings. Properly print boolean values with var_dump().
- Converting Integer to Boolean
- Converting String to Boolean
- Converting Boolean to Integer
- Properly Printing Boolean Values
- Other Ways to Cast to Boolean
- Explicitly Converting Values to Bool
- Converting Any Value to Boolean
- How to typecast a variable to boolean in PHP?
- How do I cast to boolean?
- How do you typecast a variable to a boolean?
- How to convert false string to bool PHP?
PHP is a popular server-side programming language used to create dynamic web pages. Converting data types in php is a common task, and this post will focus on converting integers, strings, and other data types to boolean. This post will provide step-by-step guidance, real-life examples , and best practices for Converting data types to boolean in PHP.
Converting Integer to Boolean
To convert an integer to a boolean in PHP, negate it twice. This can be done by using the !! operator before the integer variable.
In this example, the value of $bool will be true. If the integer value is 0, then the boolean value will be false.
Converting String to Boolean
To convert a string to a boolean, use the (bool) or (boolean) casts. However, it is unnecessary in most cases. PHP has a built-in way to automatically convert strings to boolean values.
In this example, the value of $bool will be true because the string value is “true”. If the string value is empty, then the boolean value will be false.
It is worth noting that the settype() function can also be used to convert a string to a boolean in PHP. This function changes the type of a variable to a specified type.
$str = 'false'; settype($str, 'bool'); In this example, the value of $str will be false.
Converting Boolean to Integer
To convert a boolean to an integer, use the filter_var() function with the FILTER_VALIDATE_BOOLEAN filter. This function returns 1 for true and 0 for false .
$bool = true; $int = filter_var($bool, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE); In this example, the value of $int will be 1.
Properly Printing Boolean Values
To properly print boolean values , use the var_dump() function instead of echo . This function displays structured information about one or more expressions that includes its type and value.
In this example, the output will be “bool(true)”.
Other Ways to Cast to Boolean
The only other way to cast to boolean is to use new Boolean(value) , but it may fail with strict comparisons to other boolean primitives. It is best to use the built-in PHP functions instead.
The boolval() function can be used to get the boolean value of a variable. This function returns true for a non-empty string or a non-zero integer, and false otherwise.
$value = 'hello'; $bool = boolval($value); In this example, the value of $bool will be true.
Explicitly Converting Values to Bool
To explicitly convert a value to bool, use the (bool) or (boolean) casts. But it is not necessary since a value will be automatically interpreted as a bool in a logical context.
$value = 'hello'; $bool = (bool)$value; In this example, the value of $bool will be true because the string value is non-empty.
The is_bool() function returns true if the type of its argument is boolean without converting or coercing the value.
$value = true; if(is_bool($value))
In this example, the output will be “$value is a boolean”.
Converting Any Value to Boolean
To convert any value to boolean in PHP, use the filter_var() function with the FILTER_VALIDATE_BOOLEAN filter.
$value = 'true'; $bool = filter_var($value, FILTER_VALIDATE_BOOLEAN); In this example, the value of $bool will be true.
converting data types to boolean in PHP is a common task that can be easily accomplished with the right knowledge and tools. By following the steps and best practices outlined in this post, developers can efficiently and effectively convert integers, strings , and other data types to boolean in PHP. Remember to use var_dump() to properly print boolean values and to optimize PHP performance and security by using best practices and resources like the PHP cheat sheet .
Php cast to boolean
Cast a string to binary using PHP < 5.2.1
I found it tricky to check if a posted value was an integer.
is_int ( $_POST [ ‘a’ ] ); //false
is_int ( intval ( «anything» ) ); //always true
?>
A method I use for checking if a string represents an integer value.
$foo [ ‘ten’ ] = 10 ; // $foo[‘ten’] is an array holding an integer at key «ten»
$str = » $foo [ ‘ten’]» ; // throws T_ENCAPSED_AND_WHITESPACE error
$str = » $foo [ ten ] » ; // works because constants are skipped in quotes
$fst = (string) $foo [ ‘ten’ ]; // works with clear intention
?>
It seems (unset) is pretty useless. But for people who like to make their code really compact (and probably unreadable). You can use it to use an variable and unset it on the same line:
$hello = ‘Hello world’ ;
print $hello ;
unset( $hello );
$hello = ‘Hello world’ ;
$hello = (unset) print $hello ;
?>
Hoorah, we lost another line!
It would be useful to know the precedence (for lack of a better word) for type juggling. This entry currently explains that «if either operand is a float, then both operands are evaluated as floats, and the result will be a float» but could (and I think should) provide a hierarchy that indicates, for instance, «between an int and a boolean, int wins; between a float and an int, float wins; between a string and a float, string wins» and so on (and don’t count on my example accurately capturing the true hierarchy, as I haven’t actually done the tests to figure it out). Thanks!
May be expected, but not stated ..
Casting to the existing (same) type has no effect.
$t = ‘abc’; // string ‘abc’
$u=(array) $t; // array 0 => string ‘abc’ $v=(array) $u; // array 0 => string ‘abc’
Correct me if I’m wrong, but that is not a cast, it might be useful sometimes, but the IDE will not reflect what’s really happening:
class MyObject /**
* @param MyObject $object
* @return MyObject
*/
static public function cast ( MyObject $object ) return $object ;
>
/** Does nothing */
function f () <>
>
class X extends MyObject /** Throws exception */
function f () < throw new exception (); >
>
$x = MyObject :: cast (new X );
$x -> f (); // Your IDE tells ‘f() Does nothing’
?>
However, when you run the script, you will get an exception.
In my much of my coding I have found it necessary to type-cast between objects of different class types.
More specifically, I often want to take information from a database, convert it into the class it was before it was inserted, then have the ability to call its class functions as well.
The following code is much shorter than some of the previous examples and seems to suit my purposes. It also makes use of some regular expression matching rather than string position, replacing, etc. It takes an object ($obj) of any type and casts it to an new type ($class_type). Note that the new class type must exist:
Looks like type-casting user-defined objects is a real pain, and ya gotta be nuttin’ less than a brain jus ta cypher-it. But since PHP supports OOP, you can add the capabilities right now. Start with any simple class.
class Point protected $x , $y ;
public function __construct ( $xVal = 0 , $yVal = 0 ) $this -> x = $xVal ;
$this -> y = $yVal ;
>
public function getX () < return $this ->x ; >
public function getY () < return $this ->y ; >
>
$p = new Point ( 25 , 35 );
echo $p -> getX (); // 25
echo $p -> getY (); // 35
?>
Ok, now we need extra powers. PHP gives us several options:
A. We can tag on extra properties on-the-fly using everyday PHP syntax.
$p->z = 45; // here, $p is still an object of type [Point] but gains no capability, and it’s on a per-instance basis, blah.
B. We can try type-casting it to a different type to access more functions.
$p = (SuperDuperPoint) $p; // if this is even allowed, I doubt it. But even if PHP lets this slide, the small amount of data Point holds would probably not be enough for the extra functions to work anyway. And we still need the class def + all extra data. We should have just instantiated a [SuperDuperPoint] object to begin with. and just like above, this only works on a per-instance basis.
C. Do it the right way using OOP — and just extend the Point class already.
class Point3D extends Point protected $z ; // add extra properties.
public function __construct ( $xVal = 0 , $yVal = 0 , $zVal = 0 ) parent :: __construct ( $xVal , $yVal );
$this -> z = $zVal ;
>
public function getZ () < return $this ->z ; > // add extra functions.
>
$p3d = new Point3D ( 25 , 35 , 45 ); // more data, more functions, more everything.
echo $p3d -> getX (); // 25
echo $p3d -> getY (); // 35
echo $p3d -> getZ (); // 45
?>
Once the new class definition is written, you can make as many Point3D objects as you want. Each of them will have more data and functions already built-in. This is much better than trying to beef-up any «single lesser object» on-the-fly, and it’s way easier to do.
Re: the typecasting between classes post below. fantastic, but slightly flawed. Any class name longer than 9 characters becomes a problem. SO here’s a simple fix:
function typecast($old_object, $new_classname) if(class_exists($new_classname)) // Example serialized object segment
// O:5:»field»:9: $old_serialized_prefix = «O:».strlen(get_class($old_object));
$old_serialized_prefix .= «:\»».get_class($old_object).»\»:»;
$old_serialized_object = serialize($old_object);
$new_serialized_object = ‘O:’.strlen($new_classname).’:»‘.$new_classname . ‘»:’;
$new_serialized_object .= substr($old_serialized_object,strlen($old_serialized_prefix));
return unserialize($new_serialized_object);
>
else
return false;
>
Thanks for the previous code. Set me in the right direction to solving my typecasting problem. 😉
If you have a boolean, performing increments on it won’t do anything despite it being 1. This is a case where you have to use a cast.
I have 1 bar.
I now have 1 bar.
I finally have 2 bar.
Checking for strings to be integers?
How about if a string is a float?
/* checks if a string is an integer with possible whitespace before and/or after, and also isolates the integer */
$isInt = preg_match ( ‘/^\s*(5+)\s*$/’ , $myString , $myInt );
echo ‘Is Integer? ‘ , ( $isInt ) ? ‘Yes: ‘ . $myInt [ 1 ] : ‘No’ , «\n» ;
/* checks if a string is an integer with no whitespace before or after */
$isInt = preg_match ( ‘/^4+$/’ , $myString );
echo ‘Is Integer? ‘ , ( $isInt ) ? ‘Yes’ : ‘No’ , «\n» ;
/* When checking for floats, we assume the possibility of no decimals needed. If you MUST require decimals (forcing the user to type 7.0 for example) replace the sequence:
7+(\.7+)?
with
4+\.1+
*/
/* checks if a string is a float with possible whitespace before and/or after, and also isolates the number */
$isFloat = preg_match ( ‘/^\s*(7+(\.2+)?)\s*$/’ , $myString , $myNum );
echo ‘Is Number? ‘ , ( $isFloat ) ? ‘Yes: ‘ . $myNum [ 1 ] : ‘No’ , «\n» ;
/* checks if a string is a float with no whitespace before or after */
$isInt = preg_match ( ‘/^9+(\.9+)?$/’ , $myString );
echo ‘Is Number? ‘ , ( $isFloat ) ? ‘Yes’ : ‘No’ , «\n» ;