std::numeric_limits<T>::max

 

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Defined in header <limits>
static T max() throw();		(until C++11)
static constexpr T max() noexcept;		(since C++11)

Returns the maximum finite value representable by the numeric type T. Meaningful for all bounded types.

Return value

T	std::numeric_limits<T>::max()
/* non-specialized */	T()
bool	true
char	CHAR_MAX
signed char	SCHAR_MAX
unsigned char	UCHAR_MAX
wchar_t	WCHAR_MAX
char8_t (since C++20)	UCHAR_MAX
char16_t (since C++11)	UINT_LEAST16_MAX
char32_t (since C++11)	UINT_LEAST32_MAX
short	SHRT_MAX
unsigned short	USHRT_MAX
int	INT_MAX
unsigned int	UINT_MAX
long	LONG_MAX
unsigned long	ULONG_MAX
long long (since C++11)	LLONG_MAX
unsigned long long (since C++11)	ULLONG_MAX
float	FLT_MAX
double	DBL_MAX
long double	LDBL_MAX

Example

Demonstrates the use of max() with some fundamental types and some standard library typedefs (the output is system-specific):

Run this code

#include <boost/type_index.hpp>
#include <cstddef>
#include <iomanip>
#include <iostream>
#include <limits>
#include <type_traits>
 
template<typename T>
void print_max_value_of()
{
    constexpr T max{std::numeric_limits<T>::max()};
 
    std::cout << std::setw(16) << boost::typeindex::type_id<T>() << ": ";
    if constexpr (std::is_floating_point_v<T>)
        std::cout << std::defaultfloat << max << " = " << std::hexfloat << max << '\n';
    else
    {
        constexpr auto m{static_cast<unsigned long long>(max)};
        std::cout << std::dec << m << " = " << std::hex << m << '\n';
    }
}
 
int main()
{
    std::cout << std::showbase;
 
    print_max_value_of<bool>();
    print_max_value_of<short>();
    print_max_value_of<int>();
    print_max_value_of<std::streamsize>();
    print_max_value_of<std::size_t>();
    print_max_value_of<char>();
    print_max_value_of<char16_t>();
    print_max_value_of<wchar_t>();
    print_max_value_of<float>();
    print_max_value_of<double>();
    print_max_value_of<long double>();
}

Possible output:

            bool: 1 = 0x1
           short: 32767 = 0x7fff
             int: 2147483647 = 0x7fffffff
            long: 9223372036854775807 = 0x7fffffffffffffff
   unsigned long: 18446744073709551615 = 0xffffffffffffffff
            char: 127 = 0x7f
        char16_t: 65535 = 0xffff
         wchar_t: 2147483647 = 0x7fffffff
           float: 3.40282e+38 = 0x1.fffffep+127
          double: 1.79769e+308 = 0x1.fffffffffffffp+1023
     long double: 1.18973e+4932 = 0xf.fffffffffffffffp+16380

See also

lowest [static] (C++11)	returns the lowest finite value of the given type, i.e. the most negative value for signed types, ​0​ for unsigned types (public static member function)
min [static]	returns the smallest finite value of the given non-floating-point type, or the smallest positive normal value of the given floating-point type (public static member function)