I don't have an old AMOS machine handy to test this against, but I can tell you that it worked the same as far back as 6.4.1558.
Although it's a bit counter-intuitive, the
STR(x) function expects
x to be a number (since after all, the purpose of the function is to convert a numeric value to a string representation). In a traditional strongly typed language like C, your
STR(S) function call would generate a compiler error (mismatched argument type). But in the world of AlphaBasic's automatic string-numeric conversion, the compiler inserts the equivalent of
VAL(S) call to convert
S to a numeric value so that
STR() can convert it from the expected number to a string. So in other words, it gets turned into
STR(VAL(S))While we're on the subject, a couple of related side notes:
Arguments passed to the
PRINT statement, as well as
XCALL and function arguments, get compiled with their own type indicators, eliminating the need for conversions based on expected types. In other words,
PRINT A does not have to assume anything about
A because the compiler inserts a type identifier into the RUN code, allowing
PRINT to select the appropriate type logic. But
PRINT STR(S) gets in the way of that intelligence by forcing a double conversion when
PRINT otherwise would have determined that none was needed.
The
+ and
= operators, on the other hand, have to determine whether to operate in string or numeric mode based on the precedent established before the operator is seen in the statement.
The
Explicit Plus Operators and
Explicit Comparison Operators provide a way to override the automatic conversion logic to make your intent explicit.
