Texas Instruments TI-99/4A - Relational Expressions

Relational Expressions
• Not equal to (< > )
• Less than or equal to « =)
• Greater than or equal to (> =)
Relational expressions are normally used in the IF-THEN·ELSE
statement but may be used anywhere numeric, expressions are
allowed. When you use relational expressions within a numeric
expression, a numeric value of -1 is given if the relation is true
and a numeric value of 0 is g-iven if the relation is false.
Relational operations
are performed from left to right before string
concatenation and after all arithmetic operations within the
expression are completed. To pertorm string concatenation before
relational operations and/or to perform relational operations before
arithmetic operations, you must use parentheses. Valid relational
operators are:
• Equal to (=)
• Less than «)
• Greater than ( »
An explanation of how string comparisons are performed to give
you a
true or false result IS discussed In the IF-THEN-ELSE
explanation. Remember that the result you obtain from the
evaluation
of a relational operator is always a number. If you try
to use the result
a5 a string. you will get an error.
II·14
Examples:
>NEW
>100 A=2<5
>-110 0-3<;-2
>120 PRINT A;8
>130
END
>RlJN
-1 0
** DONE **
>NEW
>100 A$="Hl"
>110 8$-" THERE!"
>120 PRINT (A$&B$)="HI!"
>130 END
>RUN
o
** DONE **
>120 PRINT (A$&B$) >"HI"
>RUN
-1
** DONE **
>120 PRINT (A$>BS)*4
>~IJN
-4
** DONE **
>NEW
>100 A=2<4*3
>110 B=A=O
>120 PRINT AiB
>130 END
>RUN
-1 0
** DONE **
User's Reference Guide