How to convert string to boolean type in php

Method: 1. Add "(bool)" or "(boolean)" before the variable to be converted to force conversion to boolean type; 2. Use the boolval() function with the syntax "boolval(value)" ;3. Use the settype() function, the syntax is "settype(value, "boolean")".

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

1. Forced type conversion-- Prepend the target type enclosed in parentheses (bool) or (boolean)

before the variable to be converted. Example:

<?php
$bool1 = (bool) &#39;ciao&#39;;
$bool2 = (boolean) &#39;0&#39;;
var_dump($bool1); 
var_dump($bool2); 
?>

Rendering:

2. Use boolval() function

boolval function is used to obtain The Boolean value of the variable.

Example:

<?php
echo &#39;0:        &#39;.(boolval(0) ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;42:       &#39;.(boolval(42) ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;0.0:      &#39;.(boolval(0.0) ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;4.2:      &#39;.(boolval(4.2) ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;"":       &#39;.(boolval("") ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;"string": &#39;.(boolval("string") ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;"0":      &#39;.(boolval("0") ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;"1":      &#39;.(boolval("1") ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;[1, 2]:   &#39;.(boolval([1, 2]) ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;[]:       &#39;.(boolval([]) ? &#39;true&#39; : &#39;false&#39;)."\n";
echo &#39;stdClass: &#39;.(boolval(new stdClass) ? &#39;true&#39; : &#39;false&#39;)."\n";
?>

Output:

0:        false
42:       true
0.0:      false
4.2:      true
"":       false
"string": true
"0":      false
"1":      true
[1, 2]:   true
[]:       false
stdClass: true

3. Use the general type conversion function settype(mixed var,string type)

<?php  
$str="123.9sdc";  
$int=settype($str,"boolean");  
var_dump($int);  
var_dump($str); 
echo "<hr>";
$str="";  
$int=settype($str,"boolean");  
var_dump($int);  
var_dump($str); 
?>

Output:

The settype() function is used to set the type of a variable.

Syntax

bool settype ( mixed &$var , string $type )

Set the type of variable var to type.

To be converted Variables. The possible values ​​of Recommended study: "

Parameters	Description
##var
type	##type are: "boolean" (or "bool" since PHP 4.2.0) "integer" (or "int" since PHP 4.2.0) "float" (only available after PHP 4.2.0, "double" used in older versions is now deprecated) "string" "array" "object" "null" (from PHP 4.2.0)

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