GWBASIC User's Manual

GW-BASIC User's Guide
A function is used in an expression to call a predetermined operation that is to be performed on
an operand. GW-BASIC has intrinsic functions that reside in the system, such as SQR (square
root) or SIN (sine).
GW-BASIC also allows user-defined functions written by the programmer. See the DEF FN
statement in the GW-BASIC User's Reference.
6.4.5 String Operators
To compare strings, use the same relational operators used with numbers:
OperatorMeaning
= Equal to
Unequal
< Less than
> Greater than
= Greater than or equal to
The GW-BASIC Interpreter compares strings by taking one character at a time from each string
and comparing their ASCII codes. If the ASCII codes in each string are the same, the strings are
equal. If the ASCII codes differ, the lower code number will precede the higher code. If the
interpreter reaches the end of one string during string comparison, the shorter string is said to be
smaller, providing that both strings are the same up to that point. Leading and trailing blanks are
significant.
For example:
"AA" < "AB"
"FILENAME" = "FILENAME"
"X&" > "X#"
"CL " > "CL"
"kg" > "KG"
"SMYTH" < "SMYTHE"
B$ < "9/12/78" where B$ = "8/12/78"
String comparisons can also be used to test string values or to alphabetize strings. All string
constants used in comparison expressions must be enclosed in quotation marks.
Strings can be concatenated by using the plus (+) sign. For example:
10 A$="FILE":B$="NAME"
20 PRINT A$+B$
30 PRINT "NEW " + A$+B$
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