In most of the programming language True and False are considered as the boolean values. But Perl does not provide the type boolean for True and False. In general, a programmer can use the term “boolean” when a function returns either True or False. Like conditional statements(if, while etc.) will return either true or false for the scalar values.
Example:
# Perl Code to demonstrate the boolean values # variable assigned value 0 $k = 0; # checking whether k is true or false if ( $k ) { print "k is True\n" ; } else { print "k is False\n" ; } # variable assigned value 2 $m = 2; # checking whether m is true or false if ( $m ) { print "m is True\n" ; } else { print "m is False\n" ; } |
Output:
k is False m is True
True Values: Any non-zero number i.e. except zero are True values in the Perl language. String constants like ‘true’, ‘false’, ‘ ‘(string having space as the character), ’00’(2 or more 0 characters) and “0\n”(a zero followed by a newline charatcer in string) etc. also consider true values in Perl.
- Example:
# Perl Code to demonstrate the True values
# variable assigned value 5
$a
= 5;
# checking whether a is true or false
if
(
$a
)
{
print
"a is True\n"
;
}
else
{
print
"a is False\n"
;
}
# string variable assigned white
# space character
$b
=
' '
;
# checking whether b is true or false
if
(
$b
)
{
print
"b is True\n"
;
}
else
{
print
"b is False\n"
;
}
# string variable assigned 'false'
# value to it
$c
=
'false'
;
# checking whether c is true or false
if
(
$c
)
{
print
"c is True\n"
;
}
else
{
print
"c is False\n"
;
}
# string variable assigned "0\n"
# value to it
$d
=
"0\n"
;
# checking whether d is true or false
if
(
$d
)
{
print
"d is True\n"
;
}
else
{
print
"d is False\n"
;
}
Output:
a is True b is True c is True d is True
False Values: Empty string or string contains single digit 0 or undef value and zero are considered as the false values in perl.
- Example:
# Perl Code to demonstrate the False values
# variable assigned value 0
$a
= 0;
# checking whether a is true or false
if
(
$a
)
{
print
"a is True\n"
;
}
else
{
print
"a is False\n"
;
}
# string variable assigned empty string
$b
=
''
;
# checking whether b is true or false
if
(
$b
)
{
print
"b is True\n"
;
}
else
{
print
"b is False\n"
;
}
# string variable assigned undef
$c
=
undef
;
# checking whether c is true or false
if
(
$c
)
{
print
"c is True\n"
;
}
else
{
print
"c is False\n"
;
}
# string variable assigned ""
# value to it
$d
=
""
;
# checking whether d is true or false
if
(
$d
)
{
print
"d is True\n"
;
}
else
{
print
"d is False\n"
;
}
Output:
a is False b is False c is False d is False
Note: For the conditional check where the user has to compare two different variables, if they are not equal it returns False otherwise True.
- Example:
# Perl Program demonstrate the conditional check
# variable initialized with string
$x
=
"GFG"
;
# using if statement
if
(
$x
eq
"GFG"
)
{
print
"Return True\n"
;
}
else
{
print
"Return False\n"
;
}
Output:
Return True