Comparing 2 items of an listbox and 2 lines of a Memo

Question

How to compare 2 items of an listbox and 2 lines of a Memo? How do I give an item of an Listbox a variabele? How do I give a line of a Memo a variabele?

Have you tried anything? Please edit your question and include the code that you've tried to write. Then ask a question specific to the code example. You question suggests you might benefit from one of many tutorials available from Embarcadero, including http://www.embarcadero.com/firemonkey/firemonkey-e-learning-series — James L., Oct 26 '13 at 06:28

NGLN · Answer 1 · 2013-10-26T08:39:09.803

ListBox items

The contents of a ListBox is stored in TListBox.Items which is of type TStrings. This is a zero-based list/array of strings, thus in order to get the second item in the ListBox call one of the following:

ListBox1.Items.Strings[1], or
ListBox1.Items[1], because Strings[] is the default property.

Memo lines

The contents of a Memo is stored in TMemo.Lines which also is of type TStrings, thus to get the first line of the Memo, call:

Memo1.Lines.Strings[0], or
Memo1.Lines[0].

Comparison/relational operators

= equality
<> inequality
< smaller
etc...

All together

Thus to compare the first line of the Memo with the second item of the ListBox, do:

if Memo1.Lines[0] <operator> ListBox1.Items[1] then

For example: when you want to check whether both are equal:

if Memo1.Lines[0] = ListBox1.Items[1] then

Going advanced

Maybe a simple comparison operator does not give enough information about the difference between the two strings. Then use a function instead of an operator to compare the two strings, see the units SysUtils and StrUtils. For example, when you want to compare both strings for having the same text, regardless case:

if SameText(Memo1.Lines[0], ListBox1.Items[1]) then

Comparing 4 items simultaneously

Concatenate two comparisons with a boolean/logic operator:

if (Memo1.Lines[0] = ListBox1.Items[0]) and (Memo1.Lines[1] = ListBox1.Items[1]) then