David Brown <david.brown@hesbynett.no> writes:Right.
[...]"42" is an expression of type "int", and so is 'printf("Hello\n")'.[...]
How (and why) would a language distinguish between them and allow one
but not the other?
Ada, Pascal, and similar languages do exactly this, for what many
people consider to be good reasons.
What I'm not sure about is the predominance of "these" or "those"
languages. - Is that clear distinction of procedures and function
the typical case, or are the "C-derived" languages predominant and
languages with a clear distinction (meanwhile?) just outliers?
There's of course also other languages that distinguish procedures
from functions "only" by the 'void' "return type", but are anyway
able to diagnose the appropriate context and emit error messages
when inappropriately used.
In both languages, functions and procedures are distinct. FunctionsErm, I hope that above printf() call does not create an error, but
return values; procedures do not. An expression cannot be turned
into a statement just by adding a semicolon. A function call is
an expression. A procedure call is a statement, not an expression.
An assignment is a statement, not an expression.
For I/O, the equivalent of printf is a procedure. In C,
printf("Hello, world\n") returns a negative result to denote an
error (and that value is often ignored).
returns the number of characters in the printed text. ;-)
Janis
[...]
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