Popular Myths about C++, Part 1

Post by maxlybbert » Tue, Dec 09, 2014, 3:50 PM UTC

mikeash wrote: post #66

jlarocco wrote: post #65

Earlier quoted context omitted.

> auto v = {1,2,3,5,8,13}; > Kaboom. Oops. You can use auto, or you can use {} to make a vector, but you can't do both at the same time! IMO it would be more confusing if that created a vector . Unless the compiler is reading your mind, how is it supposed to know you meant a vector , a set , deque , a struct { int a,b,c,d,e,f}, or some other object who's constructor can take 6 ints?

The way most other languages handle it is that the list literal construct just creates a list, and if you want something else then you need to explicitly convert. For example, in Python: x = [1, 2, 3, 5, 8, 13] # this is a list of integers y = set([1, 2, 3, 5, 8, 13]) # this is a set of integers There's nothing inherently wrong with C++'s initializer list approach. Nor is there anything inherently wrong with auto. Bu…

Post by jerf » Tue, Dec 09, 2014, 3:57 PM UTC

jlarocco wrote: post #65

mikeash wrote: post #40

A major problem with C++ is a lack of consistency, which you run into if you start trying to generalize the ideas presented in this article. The article demonstrates string concatenation using +. That is great! Except it's inconsistent. The article's example works fine, of course: return name+'@'+domain; I'll skip over the weird use of '' instead of "". Now let's say I want to prepend mailto: as well: return "mailto:…

> auto v = {1,2,3,5,8,13}; > Kaboom. Oops. You can use auto, or you can use {} to make a vector, but you can't do both at the same time! IMO it would be more confusing if that created a vector . Unless the compiler is reading your mind, how is it supposed to know you meant a vector , a set , deque , a struct { int a,b,c,d,e,f}, or some other object who's constructor can take 6 ints?

    v := []TYPEHERE{1, 2, 3}

Post by jerf » Tue, Dec 09, 2014, 4:01 PM UTC

bkeroack wrote: post #45

millstone wrote: post #20

Earlier quoted context omitted.

Much of C++ can only be understood in the context of C. For example, why are string literals not std::string, and what the heck are null-terminated strings about? In your alternate universe, C++ would be a nonsense language full of absurd design decisions. Understanding C is perhaps necessary to understand why C++ works the way it does.

Even further, why are strings considered a linear sequence of 8-bit characters (defaulting to ASCII)? That's madness in 2014! If I give you a sequence of bytes and tell you it's a "string", that's no more meaningful than if I gave you a bunch of bytes and said "this is music" or "this is a picture". Without telling you the encoding you have to blindly guess how to interpret it. Go does a good job of rectifying this:…

Post by antimagic » Tue, Dec 09, 2014, 4:09 PM UTC

mikeash wrote: post #44

ExpiredLink wrote: post #30

Earlier quoted context omitted.

> Drives me batty to see articles where malloc() is happily assumed to always succeed. ... as in Linux.

Malloc will never fail on Linux due to running out of RAM . However, it will fail for other reasons, such as running out of address space. You can easily run out of address space in 32-bit processes, since you only have 4GB of address space, or less. It's much harder in 64-bit processes, but since you can allocate vast chunks of memory without having them be backed by RAM, you can accomplish it there as well.

Post by throwawayaway » Tue, Dec 09, 2014, 4:12 PM UTC

maxlybbert wrote: post #87

throwawayaway wrote: post #21

Earlier quoted context omitted.

why do pointers exist if you have references? why does printf exist? what is everything in the cstdlib?

> why do pointers exist if you have references? Because references can't be NULL in C++, and you can't reseat a reference in C++. > why does printf exist? Personally, I think the more interesting question is "why isn't printf extensible?" And, with variable length template functions, it should now be extensible. If it were converted to a template. > what is everything in the cstdlib? I can't speak for all beginners,…