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The maximum length for a string is 65,535 characters. A restriction of the
DECTPU compiler is that a string constant (an open quotation mark, some
characters, and a close quotation mark) must have both its opening and closing
quotation marks on the same line. While a string can be up to 65,535 characters
long, a line in a DECTPU buffer can only be 32767 characters long. If you try
to create a line that is longer than 32767 characters, DECTPU truncates the
inserted text to the amount that fills the line to 32767 characters.
Many DECTPU built-in procedures return a value of the string data type. The
ASCII built-in procedure, for example, returns a string for the ordinal value that
you use as a parameter. The following statement returns the string
variable my_char:
my_char := ASCII (75);
To replicate a string, specify the string to be reproduced, then the multiplication
operator ( * ), and then the number of times you want the string to be replicated.
For example, the following DECTPU statement inserts 10 underscores into the
current buffer at the editing point:
COPY_TEXT ("_" * 10)
The string to be replicated must be on the left-hand side of the operator. For
example, the following DECTPU statement produces an error:
COPY_TEXT (10 * "_")
To reduce a string, specify the string to be modified, then the subtraction operator
(–), and then the substring to be removed. Table 3–2 shows the effects of two
string-reduction operations.
Table 3–2 Effects of Two String-Reduction Operations
DECTPU Statement
COPY_TEXT ("FILENAME.MEM"–"FILE")
COPY_TEXT ("woolly"–"wool")
3.12 Unspecified Data Type
An unspecified value is the initial value of a variable after it has been compiled
(added to the DECTPU symbol table). In the following example, the COMPILE
built-in procedure creates the variable x and initially gives it the data type
unspecified unless x has previously been declared as a global variable:
COMPILE ("x := 1");
An assignment statement that creates a variable must be executed before a data
type is assigned to the variable. In the following example, when you use the
EXECUTE built-in procedure to run the program that is stored in the variable
prog, the variable x is assigned an integer value:
prog := COMPILE ("x := 1");
EXECUTE (prog);
DEC Text Processing Utility Data Types
3.11 String Data Type
Result
Inserts the string "NAME.MEM" into
the current buffer at the editing point.
Inserts the string "ly" into the current
buffer at the editing point.
DEC Text Processing Utility Data Types 3–21
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in the
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