Empty string

Empty string is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Some languages have syntax or semantics for dealing specifically with empty strings.

The task is to:

• Demonstrate how to assign an empty string to a variable.
• Demonstrate how to check that a string is empty
• Demonstrate how to check that a string is not empty.

Java

String.isEmpty() is part of Java 1.6. Other options for previous versions are noted. <lang java5>String s = ""; if(s != null && s.isEmpty()){//optionally, instead of "s.isEmpty()": "s.length() == 0" or "s.equals("")"

  System.out.println("s is empty");

}else{

  System.out.println("s is not empty");

}</lang>

Perl 6

In Perl 6 we can't just test a string for truth to determine if it has a value. The string "0" will test as false even though it has a value. Instead we must test for length.

<lang perl6>my $s = ; say 'String is empty' unless $s.chars; say 'String is not empty' if $s.chars;</lang>

Python

<lang python>s = if not s:

   print('String s is empty.')

if s:

   print('String s is not empty.')</lang>