Compaq AA-PWCBD-TE manual Arithmetic Expressions, Relational Expressions

Lexical Elements of the DEC Text Processing Utility Language 4.8 Expressions

There are four types of DECTPU expressions:

•Arithmetic

•Relational

•Pattern

•Boolean

The following sections discuss each of these expression types.

4.8.1 Arithmetic Expressions

You can use any of the arithmetic operators (+, –, *, / ) with integer data types to form arithmetic expressions. DECTPU performs only integer arithmetic. The following are examples of valid DECTPU expressions:

12 + 4	!	adds two integers
"abc" + "def"	!	concatenates two strings

The following is not a valid DECTPU expression because it mixes data types:

"abc" + 12 ! you cannot mix data types

When performing integer division, DECTPU truncates the remainder; it does not round. The following examples show the results of division operations:

Expression			Result
39	/	10	3
-39	/	10	-3

4.8.2 Relational Expressions

A relational expression tests the relationship between items of the same data type and returns an integer result. If the relationship is true, the result is integer 1; if the relationship is false, the result is integer 0.

Use the following relational operators with any of the DECTPU data types:

•Not equal operator (<>)

•Equal operator ( = )

For example, the following code fragment tests whether string1 starts with a letter that occurs later in the alphabet than the starting letter of string2:

string1 := "gastropod"; string2 := "arachnid"; IF string1 > string2

THEN

MESSAGE ("Out of alphabetical order ");

ENDIF;

Use the following relational operators for comparisons of integers, strings, or markers:

•Greater than operator (>)

•Less than operator (<)

•Greater than or equal to operator (>=)

•Less than or equal to operator (<=)

4–10Lexical Elements of the DEC Text Processing Utility Language