PHP

boolean to string php

echo json_encode(true);  // string "true"

echo json_encode(false); // string "false"

// null !== false
echo json_encode(null);  // string "null"

string to bool php

boolval('false');

string to boolean php

filter_var(    true, FILTER_VALIDATE_BOOLEAN); // true
filter_var(    'true', FILTER_VALIDATE_BOOLEAN); // true
filter_var(         1, FILTER_VALIDATE_BOOLEAN); // true
filter_var(       '1', FILTER_VALIDATE_BOOLEAN); // true
filter_var(      'on', FILTER_VALIDATE_BOOLEAN); // true
filter_var(     'yes', FILTER_VALIDATE_BOOLEAN); // true

filter_var(   false, FILTER_VALIDATE_BOOLEAN); // false
filter_var(   'false', FILTER_VALIDATE_BOOLEAN); // false
filter_var(         0, FILTER_VALIDATE_BOOLEAN); // false
filter_var(       '0', FILTER_VALIDATE_BOOLEAN); // false
filter_var(     'off', FILTER_VALIDATE_BOOLEAN); // false
filter_var(      'no', FILTER_VALIDATE_BOOLEAN); // false
filter_var('asdfasdf', FILTER_VALIDATE_BOOLEAN); // false
filter_var(        '', FILTER_VALIDATE_BOOLEAN); // false
filter_var(      null, FILTER_VALIDATE_BOOLEAN); // false

php convert string to boolean

/**
 * Strings always evaluate to boolean true unless they have a
 * value that's considered "empty" by PHP (taken from the
 * documentation for empty):
 * "" (an empty string) evaluates as false.
 * "0" (0 as a string) evaulates as false.
 * If you need to set a boolean based on the text value of a
 * string, then you'll need to check for the presence or
 * otherwise of that value.
 */
$boolean = $string === 'true' ? true: false;

php boolean to string

$converted_res = $res ? 'true' : 'false';

php convert to boolean

// (PHP 5 >= 5.5.0, PHP 7)
// boolval — Get the boolean value of a variable
boolval ( mixed $var ) : bool
// Returns the boolean value of var.