What's the C++ equivalent of UINT32_MAX?
Solution 1
Not sure about uint32_t
, but for fundamental types (bool
, char
, signed char
, unsigned char
, wchar_t
, short
, unsigned short
, int
, unsigned int
, long
, unsigned long
, float
, double
and long double
) you can use the numeric_limits
templates via #include <limits>
.
cout << "Minimum value for int: " << numeric_limits<int>::min() << endl;
cout << "Maximum value for int: " << numeric_limits<int>::max() << endl;
If uint32_t
is a #define
of one of the above than this code should work out of the box
cout << "Maximum value for uint32_t: " << numeric_limits<uint32_t>::max() << endl;
Solution 2
std::numeric_limits<T>::max()
defines the maximum value for type T
.
Solution 3
Well, uint32_t will always be 32 bit, and always be unsigned, so you can safely define it manually:
#define UINT32_MAX (0xffffffff)
You can also do
#define UINT32_MAX ((uint32_t)-1)
Solution 4
I can't comment so here is my input on Glen vs Lior Kogan's answer.
If you are using static variables you will run into the problem that if you assign a constant value inside a class to numeric_limits::max() that value will be in fact set to zero because of the order of initialization (see this post zero initialization and static initialization of local scope static variable)
So in that case it will only work by using Lior Kogan's answer.
// This looks cleaner, less error prone and easier to read than the other suggested by Lior Kogan
#define UINT32_MAX ((uint32_t)-1)
Solution 5
You may be able to eliminate the #include
order problems by changing your build process to define the __STDC_LIMIT_MACROS
symbol on the compiler command line instead:
cxx -D__STDC_LIMIT_MACROS ...
Of course, you would still have trouble if a header #undef
s this symbol.
Also, the authors of the standard library implementation that you are using might not have intended for users to set that particular symbol; there might be a compiler flag or a different symbol that users are intended to use to enable C99 types in C++.
kdt
Updated on July 09, 2022Comments
-
kdt almost 2 years
In C99, I include
stdint.h
and that gives meUINT32_MAX
as well asuint32_t
data type. However, in C++ theUINT32_MAX
gets defined out. I can define__STDC_LIMIT_MACROS
before includingstdint.h
, but this does not work if someone is including my header after already includingstdint.h
themselves.So in C++, what is the standard way of finding out the maximum value representable in a
uint32_t
? -
Exectron about 11 yearsor if
uint32_t
is atypedef
of one of the above? -
John about 11 yearsI sure hope it's a typedef. If your tools use a
#define
for that, I question their quality. -
John about 11 yearsWe don't need to resort to that when we have perfectly valid standard C++ constructs that use only 3 times as many characters.
-
Ben Voigt over 10 years@John: This is perfectly standard and portable as well.
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o'aoughrouer over 10 yearsIn order to avoid numeric_limits::min(), numeric_limits::max() from being confused with std::min() and std::max() I had to enclose it in parentheses like this: (std::numeric_limits::max)();
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mmtauqir over 9 yearsAnd the standard libraries might not always be available - for kernel module code e.g. ...
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Aconcagua about 6 yearsI'd consider this only a fall back solution if neither of <limits>, <cstdint> nor <stdint.h> are available. But then, yes...