ADA 95 section 1

Tutorial

Basic Integer Comparison

When comparison between integers is being checked, relational operators will be used. Relational operators are listed in Table 1.

Table 1 Relational Operators
Equality test	=
Non Equality test	/=
Less Than	<
Less Than or Equal	<=
Greater Than	>
Greater Than or Equal	>=

Comparison of real numbers requires a little caution in programming. Standard comparisons such as 'A = B' or 'C = 3.14' may not work properly in a program. The real number may not be stored in memory exactly the way it was entered. This is computer dependent and may cause problems when a program is executed on a different machine. Figure 1 shows an example of a simple program, which was tested on a GNAT compiler, that compares two integers which a user enters.

Figure 1 Integer comparison code example
with Ada.Integer_Text_IO, Ada.Text_IO; use Ada.Integer_Text_IO, Ada.Text_IO; procedure Integer_Compare is First_In, Second_In : Integer; Test : Character := 'C'; begin while Test = 'C' or Test = 'c' loop -- Input comparison to see if user wants to remain in loop New_Line; New_Line; -- 2 carriage returns Put ("Enter a whole number: "); -- output to screen Get (First_In); -- input from keyboard Put ("Enter another whole number: "); Get (Second_In); if First_In > Second_In then -- Greater than comparison Put (First_In); Put (" is larger than"); Put (Second_In); elsif Second_In > First_in then -- Less than comparison Put (Second_In); Put (" is larger than"); Put (First_In); else -- Put ("Both numbers are the same"); end if; New_Line; New_Line; -- Note two operations can be on one line when separated by a semi-colon Put ("Enter 'E' to exit or 'C' to continue: "); Get (Test); New_Line; New_Line; end loop; end Integer_Compare;

When this program is run it would look like

Enter a whole number:   5
Enter another whole number:   23
23 is larger than       5

Enter 'E' to exit or 'C' to continue: E

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