We all know that the "gets" function from the Standard C Library (which
is part of the Standard C++ Library) is dangerous. It provides no
bounds check, so it's easy to overwrite memory when using it, and
impossible to guarantee that it won't happen.
Therefore, i think it's surprising that this function has not been
deprecated.
The C++98 Standard keeps it from the C89 standard.
The C99 Standard has kept it :-o.
Now, the C standard committee is working on safe functions (the ones
that end with "_s") for the C Standard Library. I don't know if they
are going to deprecate the dreaded "gets". Even if not, i think it
would be a good idea to deprecate it in the next C++ standard, since
C++ has better ways to accomplish the same task (getline). It's too
early to expect the safe functions (*_s) in the C++ Standard, but
getting rid of "gets" is not that hard, isn't it? Programs that use it
are broken anyway. Also, C++ has deprecated other features from C just
because C++ has better alternatives (static meaning "internal linkage"
and headers ending in ".h").
Opinions? Should this message be posted on comp.std.c++?
32  3795 
Marcus wrote: Opinions? Should this message be posted on comp.std.c++?
You probably want to post it over there, as people on here generally
focus more on application, and less on changing / debating the
standard.
Be careful with the assumption that all things using gets are
inherantly flawed however. =P
Josh Mcfarlane wrote: Be careful with the assumption that all things using gets are
inherantly flawed however. =P
Well, gets invokes undefined behavior.
Rolf Magnus wrote: Well, gets invokes undefined behavior.
From a buffer overrun? If not, what else causes the undefined behavior?
Josh Mcfarlane wrote: Rolf Magnus wrote: Well, gets invokes undefined behavior.
From a buffer overrun? If not, what else causes the undefined behavior?
Many functions in the C library have undefined behavior when given
arguments outside their range. They are by and large a piece of
inherited crap that should have never received standard status (the
STDIO part of the library is the most misdesigned malodious thing
ever foisted on the community, it was derived from a misnamed
piece of crap from an ancient UNIX project called the "portable
IO library").
Ron Natalie wrote: Many functions in the C library have undefined behavior when given
arguments outside their range. They are by and large a piece of
inherited crap that should have never received standard status (the
STDIO part of the library is the most misdesigned malodious thing
ever foisted on the community, it was derived from a misnamed
piece of crap from an ancient UNIX project called the "portable
IO library").
Well, ya, my point was, if you can confine to arguments within their
range, they do function (at least to my knowledge). Good? No, but still
functionable.
Anywho, let's go throw this at the std people and see if it can get any
support.
> Many functions in the C library have undefined behavior when given arguments outside their range. They are by and large a piece of
inherited crap that should have never received standard status (the
STDIO part of the library is the most misdesigned malodious thing
ever foisted on the community, it was derived from a misnamed
piece of crap from an ancient UNIX project called the "portable
IO library").
Wow! I had never hear about that, can you explain a little more what
are the problems of <stdio.h>?
Gaijinco wrote: Many functions in the C library have undefined behavior when given
arguments outside their range. They are by and large a piece of
inherited crap that should have never received standard status (the
STDIO part of the library is the most misdesigned malodious thing
ever foisted on the community, it was derived from a misnamed
piece of crap from an ancient UNIX project called the "portable
IO library").
Wow! I had never hear about that, can you explain a little more what
are the problems of <stdio.h>?
Functions like gets that have no provisions for safety.
All the functions have arguments in different order. Some
of them have the file stream arg first, some last.
fwrite/fread have a number of records and record size number
that nobody knows what to do with other than multiply together.
It just goes on from their, the library is crap.
This propensity for undefined behaviour is an example of Design by
Contract (DbC): you meet the preconditions, and you get the contracted
behaviour. The philosophy says: if you stuff up, and fail to pick it
up in your testing, it's your fault and you're a pathetic excuse for a
programmer, (and probably a human being). Anyway, the point is that
DbC can work, but you have to guarantee the preconditions. For gets,
they're extreme: if you know that standard input necessarily sends
lines below a certain length, then you can use it. This is probably
only the case when standard input is coming from some other source that
you control. For example, you might write a filter that works on some
fixed-length records, and is designed to be used in a pipeline ala
(UNIX) "cat file | filter" or (DOS) "type file | filter". Who's to say
that you don't know what you're doing well enough to guarantee the line
length precondition? It's your own call whether you use it.
FWIW, I dislike DbC and agree that gets should hardly ever be used,
would happily consider that it should never be used in new code, but
wouldn't go to the extent of saying that it must never be used and it's
worth breaking existing code using it. More generally, the stdio
library has proven itself a well-designed bit of work, in that while
it's error-proneness been the cause of innumerable errors, it's
concision, usability and flexibility has supported innumerable systems
that do useful work. If you think you can write better in C, go ahead
and see if anyone wants to use your creations.... One of the
compromises of C++ is that it should overwhelmingly be a superset of C,
with benefits in porting, skills transfer etc..
Tony
Josh Mcfarlane wrote: Ron Natalie wrote: Many functions in the C library have undefined behavior when given
arguments outside their range. They are by and large a piece of
inherited crap that should have never received standard status (the
STDIO part of the library is the most misdesigned malodious thing
ever foisted on the community, it was derived from a misnamed
piece of crap from an ancient UNIX project called the "portable
IO library").
Well, ya, my point was, if you can confine to arguments within their
range, they do function (at least to my knowledge). Good? No, but still
functionable.
The problem about gets is that there is no way for the program to provide
arguments that are really 100% safe. gets will produce a buffer overflow if
the buffer you provided isn't large enough for the incoming data. There is
no (portable) way to make the buffer big enough in every case, since the
program can't control the amount of data that is read. This lack of control
leads me to the conclusion that gets() can be seen as generally invoking
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