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Perl | Boolean Values
• Difficulty Level : Medium
• Last Updated : 15 Feb, 2019

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
```
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