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Empty String Check◄╣

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► KB ► To/From Guides ► C++/CLI ► Tool Basics

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Empty String Check (Cross Ref > Tool Basics)

By Mike Prestwood

C++/CLI versus Delphi Prism: A side by side comparison between C++/CLI and Delphi Prism.

Operators

A language symbol used for assignment, comparison, computational, or as a logical.

Empty String Check

[Other Languages]

Languages Focus

An empty string is a zero length string, a string that is equal to null (""), or not assigned. In some languages, you can check if a string is empty by comparing it to an empty string (""). Some languages distinguish between nil and null ("") so checking if the length is 0 is easier.

C++/CLI: String.IsNullOrEmpty

The .Net framework offers a static method in the string class: String.IsNullOrEmpty.

Syntax Example:

String^ s;

//s = ""; //Uncomment to test 2nd case.

if (String::IsNullOrEmpty(s))
{
  MessageBox::Show("empty string");
}

Delphi Prism: length

In Prism, a string can be nil (unassigned), assigned an empty string (""), or assigned a value. Therefore, to check if a string is empty, you have to check against both nil and (""). Alternatively, you can check the length of the string or use String.IsNullOrEmpty.

Syntax Example:

var s: String;

if (s = nil) or (s = '') then
  MessageBox.Show("empty string");

or use length:

if length(s) = 0 then
  MessageBox.Show("empty string");

Delphi Prism Empty String Check (length)