Questions tagged [standards-compliance]
400 questions
52
votes
5 answers
Can a destructor be recursive?
Is this program well-defined, and if not, why exactly?
#include
#include
struct X {
int cnt;
X (int i) : cnt(i) {}
~X() {
std::cout << "destructor called, cnt=" << cnt << std::endl;
if ( cnt-- >…
Cubbi
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47
votes
7 answers
How universally is C99 supported?
How universally is the C99 standard supported in today's compilers? I understand that not even GCC fully supports it. Is this right?
Which features of C99 are supported more than others, i.e. which can I use to be quite sure that most compilers will…
Eli Bendersky
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43
votes
5 answers
Why class { int i; }; is not fully standard-conformant?
This is a follow-up question.
In the previous question, @JohannesSchaub-litb said that the following code is not fully standard-conformant:
class { int i; }; //unnamed-class definition. § 9/1 allows this!
and then he added,
while it is…
Nawaz
- 353,942
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37
votes
6 answers
Using the correct, or preferable, not equal operator in MySQL
Which of the two (semantically equivalent) ways is preferable to test for inequality?
'foo' != 'bar' (exclamation mark and equals sign)
'foo' <> 'bar' (less than and greater than chevron symbols together)
The MySQL documentation clearly indicates…
Rob Van Dam
- 7,812
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34
votes
3 answers
Gnu C++ macro __cplusplus standard conform?
The Gnu C++ compiler seems to define __cplusplus to be 1
#include
int main() {
std::cout << __cplusplus << std::endl;
}
This prints 1 with gcc in standard c++ mode, as well as in C++0x mode, with gcc 4.3.4, and gcc 4.7.0.
The C++11…
towi
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34
votes
3 answers
Valid characters for URI schemes?
I was thinking about Registering an Application to a URL Protocol and I'd like to know, what characters are allowed in a scheme?
Some examples:
h323 (has numbers)
h323:[@][:][;]
z39.50r (has a . as…
Camilo Martin
- 37,236
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32
votes
4 answers
Most efficient standard-compliant way of reinterpreting int as float
Assume I have guarantees that float is IEEE 754 binary32. Given a bit pattern that corresponds to a valid float, stored in std::uint32_t, how does one reinterpret it as a float in a most efficient standard compliant way?
float…
yuri kilochek
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31
votes
4 answers
Should I learn XML 1.0 or XML 1.1?
I know that a well-formed XML 1.1 is not necessarily a well-formed XML 1.0 and vice-versa.
I want to learn xml formally and i was wondering whether i should learn XML 1.0 or XML 1.1? I mean would it be more effective to learn XML 1.0 or would it be…
Pacerier
- 86,231
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- 634
28
votes
2 answers
__USE_FILE_OFFSET64 vs. _FILE_OFFSET_BITS=64
I am trying to maintain code that compiles on lots of different systems. I've seen a dozen different ways of asking for lseek that takes 64-bits. Some systems use lseek64, some use lseeko, some require that you define _FILE_OFFSET_BITS=64, and now I…
vy32
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26
votes
2 answers
Do I have the guarantee that sizeof(type) == sizeof(unsigned type)?
The sizeof char, int, long double... can vary from one compiler to another. But do I have the guarantee according to the C++11 or C11 standard that the size of any signed and unsigned fundamental integral type is the same ?
Vincent
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25
votes
1 answer
Narrowing conversion to bool in list-initialization - strange behaviour
Consider this piece of C++11 code:
#include
struct X
{
X(bool arg) { std::cout << arg << '\n'; }
};
int main()
{
double d = 7.0;
X x{d};
}
There's a narrowing conversion from a double to a bool in the initialization of x.…
bogdan
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24
votes
6 answers
How do I provide a default implementation for an Objective-C protocol?
I'd like to specify an Objective-C protocol with an optional routine. When the routine is not implemented by a class conforming to the protocol I'd like to use a default implementation in its place. Is there a place in the protocol itself where I…
fbrereto
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23
votes
4 answers
What's the difference between "dead code" and "unreachable code"?
I thought those terms where synonymous, but a note in MISRA regarding dead code indicates this to be wrong? What's the difference? Is one a subset of the other?
Lord_Gestalter
- 500
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21
votes
2 answers
What are the WONTFIX bugs on GNU/Linux and how to work around them?
Both Linux and the GNU userspace (glibc) seem to have a number of "WONTFIX" bugs, i.e. bugs which the responsible parties have declared their unwillingness to fix despite clearly violating the requirements of ISO C and/or POSIX, but I'm unaware of…
R.. GitHub STOP HELPING ICE
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21
votes
4 answers
On the std::abs function
Is the std::abs() function well defined for ALL arithmetic types in C++11 and will return |x| with no problem of approximation?
A weird thing is that with g++4.7, std::abs(char), std::abs(short int), std::abs(int), std::abs(long int) and…
Vincent
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