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true(1) [v7 man page]

TRUE(1) 						      General Commands Manual							   TRUE(1)

NAME
true, false - provide truth values SYNOPSIS
true false DESCRIPTION
True does nothing, successfully. False does nothing, unsuccessfully. They are typically used in input to sh(1) such as: while true do command done SEE ALSO
sh(1) DIAGNOSTICS
True has exit status zero, false nonzero. TRUE(1)

Check Out this Related Man Page

IS_STRING(3)								 1							      IS_STRING(3)

is_string - Find whether the type of a variable is string

SYNOPSIS
bool is_string (mixed $var) DESCRIPTION
Finds whether the type given variable is string. PARAMETERS
o $var - The variable being evaluated. RETURN VALUES
Returns TRUE if $var is of type string, FALSE otherwise. EXAMPLES
Example #1 is_string(3) example <?php $values = array(false, true, null, 'abc', '23', 23, '23.5', 23.5, '', ' ', '0', 0); foreach ($values as $value) { echo "is_string("; var_export($value); echo ") = "; echo var_dump(is_string($value)); } ?> The above example will output: is_string(false) = bool(false) is_string(true) = bool(false) is_string(NULL) = bool(false) is_string('abc') = bool(true) is_string('23') = bool(true) is_string(23) = bool(false) is_string('23.5') = bool(true) is_string(23.5) = bool(false) is_string('') = bool(true) is_string(' ') = bool(true) is_string('0') = bool(true) is_string(0) = bool(false) SEE ALSO
is_float(3), is_int(3), is_bool(3), is_object(3), is_array(3). PHP Documentation Group IS_STRING(3)
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