Commodore Plus 4 - Page 175

Using Text Strings 163
thereby moving the cursor up one line. Line 200 goes back to the message printed
by line 120 and alters the message if X is less than zero after line 130.
100 IITPUTX
ISO PRINT"ACCEPTABLE CONDITIONS"
130 X=X-4
140 IP X>0 THEN 1OO
160 X$=CHR$(27)+CHR$(65)
180 Y$=CHR$(S7)+CHR$(87)
200 PRINT Y$+X$+"WARNING! UN";
RUN
? 3
WARNING! UNACCEPTABLE CONDITIONS
Note that if you set a screen window, turn on automatic insert mode, turn off
scrolling, or reduce the screen display size during a program, these continuous
ESCape functions will remain in effect after the program has finished running.
Using Text Strings
A text string can contain up to 255 characters, including blank spaces. Any
character can appear within a literal constant text string except for a quotation
mark. A quotation mark delineates the opening or closing of a literal constant
text string and cannot appear as a character within a string. If you want to include
a quotation mark within a text string, you must use the CHR$ value for the
quotation mark, which is 34.
Literal constant text strings must be typed in quotation marks except when
they appear as constants in a DATA list. Quotation marks are optional for strings
in a DATA list unless they contain colons or commas.
Text-String Variables
A text-string variable can represent any text string. Text-string variables have a $
sign as the final character in the variable name (e.g., X$, W2$).
When you assign a text string to a variable, you must use a text-string variable.
A TYPE MISMATCH error occurs if you assign a text-string constant to a
different type of variable or you assign a number to a text-string variable. If a
number is included in a text string, the number is considered to be part of the text
string, has no mathematical value, and cannot be used in any mathematical
operation.
An.empty text-string variable is called a null string. It has length zero and can