5 ms·

While you are not wrong, the two major problems in C I would consider to be array-to-pointer decay (arrays should really have been a separate type), and assignm

While you are not wrong, the two major problems in C I would consider to be array-to-pointer decay (arrays should really have been a separate type), and assignments being expressions instead of statements. Array decay means that pointers need the ability to point to different array elements, thus requiring pointer arithmatic - something that wouldn't have been needed at all without array to pointer decay. And since assignments are expressions, they must return something, meaning they can be used in statements like 'if (a=b)...'. If they were statements they wouldn't return anything, so this mistake would be impossible. You'd lose assignment chaining, but the win here would be much greater than the loss. If I had a third choice, it would be the mess around 'char'. At the very least there should have been two types: one for characters (where signedness is irrelevant), and one for the smallest type of integers (that can exist in signed or unsigned form). And in these modern times an additional type, something like 'byte', would be needed to deal with aliasing issues, so char (and things like uint8_t) can exist without that, allowing better optimisation for those types.

eMSF 5y ago
Arrays are a separate type.
- SkeuomorphicBee 5y ago
  Just in the exact scope in which they were declared, once they are passed as argument to any function they become a simple pointer.
- agent327 5y ago
  Not from pointers, though.
nsajko 5y ago
I also dislike array-to-pointer decay, but I'm not sure why do you say that it is one of the two major problems. Could you expand on "Array decay means that pointers need the ability to point to different array elements, thus requiring pointer arithmatic"? I don't see what you mean. A point that comes to mind is that if array-to-pointer decay were really such a bad thing, the "struct of array" and "pointer to array" types would be used much more than they are (they are almost never used).
- agent327 5y ago
  If arrays are separate types, pointer arithmetic becomes redundant: you can't add one to a pointer to get to the next element anymore. That would remove an entire class of problems. Pointer to array would still be a thing, of course, but it would always only point to the _array_, without the ability to manipulate it to point to another part of the array.
  - adrian_b 5y ago
    Pointer arithmetic is not needed any more only when the programming language provides high-level operations with arrays, like APL, J, K and similar languages. A very good optimizing compiler could generate a code for accessing the arrays that would use either indices or pointers, depending on the target CPU and on the desired operation. Otherwise, if you have to write explicit loops and the compiler is not extremely clever, for optimal performance you might need to use pointers instead of indices in many cases. The optimal choice can differ between target CPUs, e.g. for Intel/AMD CPUs indices are often better than pointers, while for ARM or POWER CPUs pointers are more frequently better.
  - pjmlp 5y ago
    You can have both, as proven by languages like Modula-2 or Object Pascal.
adrian_b 5y ago
Assignments being expressions is frequently very useful for avoiding to write the same expressions twice, which could also be a source of errors. You are right about the errors caused by unintended assignments, but the root cause for these errors is not the fact that assignments are expressions, but the fact that in B & C they have replaced the operators inherited by BCPL from ALGOL, ":=" for assignment and "=" for equality test with "=" and "==". With the original operators, typos would have been very unlikely. This misguided substitution was justified by less typing, but a much better solution would have been to not change the syntax of the language but to just modify their text editor to insert ":=" when pressing ":", because deleting the "=" when not needed would have been required very seldom, as ":" in labels or "?:" is encountered much less frequently than both assignments and equality tests.
- agent327 5y ago
  If you have the same expression twice as part of a compound assignment, there's nothing stopping you from assigning the variable instead of repeating the expression: a = b = f(); vs. a = f(); b = a; And tangential, but editors really shouldn't be mangling text as you type. Whenever I install Visual Studio anywhere, it's the first thing I turn off...

eMSF 5y ago

Arrays are a separate type.

SkeuomorphicBee 5y ago
Just in the exact scope in which they were declared, once they are passed as argument to any function they become a simple pointer.
agent327 5y ago
Not from pointers, though.

nsajko 5y ago

I also dislike array-to-pointer decay, but I'm not sure why do you say that it is one of the two major problems. Could you expand on "Array decay means that pointers need the ability to point to different array elements, thus requiring pointer arithmatic"? I don't see what you mean. A point that comes to mind is that if array-to-pointer decay were really such a bad thing, the "struct of array" and "pointer to array" types would be used much more than they are (they are almost never used).

agent327 5y ago
If arrays are separate types, pointer arithmetic becomes redundant: you can't add one to a pointer to get to the next element anymore. That would remove an entire class of problems. Pointer to array would still be a thing, of course, but it would always only point to the _array_, without the ability to manipulate it to point to another part of the array.
- adrian_b 5y ago
  Pointer arithmetic is not needed any more only when the programming language provides high-level operations with arrays, like APL, J, K and similar languages. A very good optimizing compiler could generate a code for accessing the arrays that would use either indices or pointers, depending on the target CPU and on the desired operation. Otherwise, if you have to write explicit loops and the compiler is not extremely clever, for optimal performance you might need to use pointers instead of indices in many cases. The optimal choice can differ between target CPUs, e.g. for Intel/AMD CPUs indices are often better than pointers, while for ARM or POWER CPUs pointers are more frequently better.
- pjmlp 5y ago
  You can have both, as proven by languages like Modula-2 or Object Pascal.

adrian_b 5y ago

Assignments being expressions is frequently very useful for avoiding to write the same expressions twice, which could also be a source of errors. You are right about the errors caused by unintended assignments, but the root cause for these errors is not the fact that assignments are expressions, but the fact that in B & C they have replaced the operators inherited by BCPL from ALGOL, ":=" for assignment and "=" for equality test with "=" and "==". With the original operators, typos would have been very unlikely. This misguided substitution was justified by less typing, but a much better solution would have been to not change the syntax of the language but to just modify their text editor to insert ":=" when pressing ":", because deleting the "=" when not needed would have been required very seldom, as ":" in labels or "?:" is encountered much less frequently than both assignments and equality tests.

agent327 5y ago
If you have the same expression twice as part of a compound assignment, there's nothing stopping you from assigning the variable instead of repeating the expression: a = b = f(); vs. a = f(); b = a; And tangential, but editors really shouldn't be mangling text as you type. Whenever I install Visual Studio anywhere, it's the first thing I turn off...