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FTFA: I have observed someone do this: _myarr[5]={0}; – they had in the .h file the definition int _myarr[5] and they remembered that this thing co

by jordigh 12y ago

FTFA: I have observed someone do this: _myarr[5]={0}; – they had in the .h file the definition int _myarr[5] and they remembered that this thing could be initialized with {0} in other contexts. What they did wouldn't compile in C++98; in C++11 it promptly assigned the int 0 to the non-existent 5th element of _myarr, and the usual hilarity ensued. Imagine how PHP would be ridiculed for this kind of little behavior – and PHP at least would never overwrite an unrelated variable with garbage. Imagine how with C++, the poor programmer will be ridiculed instead. Let me repeat that one more time, the poor programmer will be ridiculed instead. From your response, (and you shouldn't be having char pointers for strings anyway) [...] experienced C++ programmers don't fall to that pit either This is what the article is about, about what you are doing again. C++ is weird, it has a bunch of unusual behaviours, and when pointed, people who fall into those traps are the ones ridiculed, instead of the language. I don't know if C++ could have been made less weird with the constraints that it had, as others have pointed out in this thread (C compatibility with no overhead). Perhaps it couldn't be. But this article is unhappy with the attitude of defending C++'s weirdness and then blaming the programmers for falling victims to this weirdness.

maxlybbert 12y ago
It isn't so much that you ridicule the programmer; it's a question of telling the programmer "don't use these things that you see mentioned in old books, we have replacements for them now." So, yes, comparing char*s is very different than calling strcmp; and if you want to use "==" to compare strings (so you don't have to remember to call strcmp), then use std::string.
deong 12y ago
"Blame" is too strong of a word, but the basic idea is that C++ provides a lot of power that PHP doesn't provide, and the price for that power is complexity. So while both languages are full of dark little corners waiting to kill you, C++'s dark little corners are there because really smart people couldn't figure out how to avoid them in all cases while still keeping the mandated design requirements, and PHP's dark little corners appear to be there because no one bothered to think anything through before banging out an interpreter. This isn't to say C++ is the best it could be. There are plenty of outright mistakes. But on the whole, C++ is weird and complicated because it had to be, at least to a much greater degree than PHP.
banachtarski 12y ago
That isn't weird. At all. The language did precisely what the programmer asked it to. When you make a language operate closely to the metal, you can expect the syntax to be more abstruse. If this kind of mistake was possible in a higher level language, I would expect that to be a language pitfall.
- fiatmoney 12y ago
  "When you make a language operate closely to the metal, you can expect the syntax to be more abstruse" It's the exact opposite. Close-to-the-metal, the syntax is actually very friendly - you've got values, and you can bash them in like a half-dozen ways. C is incredibly simple (I suppose their pointer syntax is a little janky, but one can always express it "one level at a time" via typedefs). The really complicated parts come from making high-level operations seem "easy". There is no close-to-the-metal notion of char* vs a string, or a lvalue vs an rvalue, let alone template metaprogramming.
  - banachtarski 12y ago
    What I should have said was provide high level abstractions while still allowing low level operations. There is an impedance mismatch that the language needs to address. Languages like Rust can get away with this by not allowing the most low level operations that are deemed unsafe and so have a more user friendly api. C on the other hand, makes no attempts at make the abstraction so the syntax is just small by definition.
- jordigh 12y ago
  You really don't think that the semantics of foo[5] = {0} vs int foo[5] = {0} being completely different in C++11 is weird?
  - banachtarski 12y ago
    They read differently so why shouldn't they be different? One has a type specification so reads like a declaration. The other doesn't. This wasn't weird before C++11 too. The only difference is that one didn't compile before (prior to the introduction of initializer lists).
inglor 12y ago
If you don't know even the most basic concepts of a language like using strings for strings that's a problem in every language. You can use an array of chars in PHP and access it by a reference and then compare pointers if you _really_ want to but you don't see people ranting on that.
- loup-vaillant 12y ago
  In C++, the following: "Hello, World!" …is a null terminated array of chars. When literal strings are not, in fact, strings, this is a problem with the language. It's confusing, you see? Underlying semantics nonwithstanding, how on Earth the followig works: (std::string)"foo" == "foo" and the following may not?! "foo" == "foo" These are not basic concepts. These are trivia. I know there are reasons for these confusing rules, but they're still confusing. You should not mock the programmer for forgetting them now and then.
  - inglor 12y ago
    Every language has quirks and issues - if you use raw char arrays like that in general purpose C++ without an extremely good reason that's not just forgetting and trivia that's a cultural issue. Just like you wouldn't see Python code relying on mutable default values or JavaScript value relying on `with` semantics or Java code relying on `URL` comparison through DNS very often - you shouldn't find code that relies on `"foo" == "foo"`. I'm sorry if my comments are harsh but I really do believe C++'s issues are mostly cultural.
    - loup-vaillant 12y ago
      So, accept the traps of the language as a fact of life, and just avoid them? No, that doesn't fly with me. Programming languages aren't Forces of Nature, they are human artefacts. They can be corrected. Of course you should never rely on `"foo" == "foo"` and other such things. Still, one would expect literal strings in the language to be of the preferred string type. C++ is the only language I know of that breaks this expectation. It does not follow the principle of least astonishment. That, is not a cultural issue. That said, I'm willing to accept that C++ do have cultural issues. Could you tell me what they are?

by jordigh 12y ago

maxlybbert 12y ago

It isn't so much that you ridicule the programmer; it's a question of telling the programmer "don't use these things that you see mentioned in old books, we have replacements for them now." So, yes, comparing char*s is very different than calling strcmp; and if you want to use "==" to compare strings (so you don't have to remember to call strcmp), then use std::string.

deong 12y ago

"Blame" is too strong of a word, but the basic idea is that C++ provides a lot of power that PHP doesn't provide, and the price for that power is complexity. So while both languages are full of dark little corners waiting to kill you, C++'s dark little corners are there because really smart people couldn't figure out how to avoid them in all cases while still keeping the mandated design requirements, and PHP's dark little corners appear to be there because no one bothered to think anything through before banging out an interpreter. This isn't to say C++ is the best it could be. There are plenty of outright mistakes. But on the whole, C++ is weird and complicated because it had to be, at least to a much greater degree than PHP.

banachtarski 12y ago

That isn't weird. At all. The language did precisely what the programmer asked it to. When you make a language operate closely to the metal, you can expect the syntax to be more abstruse. If this kind of mistake was possible in a higher level language, I would expect that to be a language pitfall.

fiatmoney 12y ago
"When you make a language operate closely to the metal, you can expect the syntax to be more abstruse" It's the exact opposite. Close-to-the-metal, the syntax is actually very friendly - you've got values, and you can bash them in like a half-dozen ways. C is incredibly simple (I suppose their pointer syntax is a little janky, but one can always express it "one level at a time" via typedefs). The really complicated parts come from making high-level operations seem "easy". There is no close-to-the-metal notion of char* vs a string, or a lvalue vs an rvalue, let alone template metaprogramming.
- banachtarski 12y ago
  What I should have said was provide high level abstractions while still allowing low level operations. There is an impedance mismatch that the language needs to address. Languages like Rust can get away with this by not allowing the most low level operations that are deemed unsafe and so have a more user friendly api. C on the other hand, makes no attempts at make the abstraction so the syntax is just small by definition.
jordigh 12y ago
You really don't think that the semantics of foo[5] = {0} vs int foo[5] = {0} being completely different in C++11 is weird?
- banachtarski 12y ago
  They read differently so why shouldn't they be different? One has a type specification so reads like a declaration. The other doesn't. This wasn't weird before C++11 too. The only difference is that one didn't compile before (prior to the introduction of initializer lists).

inglor 12y ago

If you don't know even the most basic concepts of a language like using strings for strings that's a problem in every language. You can use an array of chars in PHP and access it by a reference and then compare pointers if you _really_ want to but you don't see people ranting on that.

loup-vaillant 12y ago
In C++, the following: "Hello, World!" …is a null terminated array of chars. When literal strings are not, in fact, strings, this is a problem with the language. It's confusing, you see? Underlying semantics nonwithstanding, how on Earth the followig works: (std::string)"foo" == "foo" and the following may not?! "foo" == "foo" These are not basic concepts. These are trivia. I know there are reasons for these confusing rules, but they're still confusing. You should not mock the programmer for forgetting them now and then.
- inglor 12y ago
  Every language has quirks and issues - if you use raw char arrays like that in general purpose C++ without an extremely good reason that's not just forgetting and trivia that's a cultural issue. Just like you wouldn't see Python code relying on mutable default values or JavaScript value relying on `with` semantics or Java code relying on `URL` comparison through DNS very often - you shouldn't find code that relies on `"foo" == "foo"`. I'm sorry if my comments are harsh but I really do believe C++'s issues are mostly cultural.
  - loup-vaillant 12y ago
    So, accept the traps of the language as a fact of life, and just avoid them? No, that doesn't fly with me. Programming languages aren't Forces of Nature, they are human artefacts. They can be corrected. Of course you should never rely on `"foo" == "foo"` and other such things. Still, one would expect literal strings in the language to be of the preferred string type. C++ is the only language I know of that breaks this expectation. It does not follow the principle of least astonishment. That, is not a cultural issue. That said, I'm willing to accept that C++ do have cultural issues. Could you tell me what they are?