C++ unsigned int 的最大值

Maximum value for unsigned int

提问by Evan Hahn

Here's what I want:

这是我想要的：

unsigned int max_unsigned_int_size;
max_unsigned_int_size = ???;

How should I do this?

我该怎么做？

回答by John Kugelman

C

C

#include <limits.h>
unsigned int max_unsigned_int_size = UINT_MAX;

C++

C++

#include <limits>
unsigned int max_unsigned_int_size = std::numeric_limits<unsigned int>::max();

回答by Jens Gustedt

unsigned int max_unsigned_int_size = -1;

is guaranteed to do the right thing. Arithmetic with unsigned types is always modulo.

保证做正确的事。无符号类型的算术总是取模的。

But in the concrete case you always should use UINT_MAX

但在具体情况下，你总是应该使用 UINT_MAX

回答by sehe

You're looking for

您正在寻找

#include <limits>
std::numeric_limits<unsigned int>::max();

If you wanted the size, sizeofwould do, multiply by CHAR_BITS to get the bits.

如果你想要大小，sizeof可以做，乘以 CHAR_BITS 得到位。

Alternattively, there is

或者，有

std::numeric_limits<unsigned int>::digits();

回答by juanchopanza

You need std::numeric_limits::max()

你需要 std::numeric_limits::max()

#include <limits>

...

max_insigned_int_size = std::numeric_limits<unsigned int>::max():

回答by David Heffernan

• For C the value is given by UINT_MAXin limits.h.
• For C++ you can alternatively use std::numeric_limits<unsigned int>::max()from limits.

• 对于 C，值由UINT_MAXin给出limits.h。
• 对于 C++，您也可以使用std::numeric_limits<unsigned int>::max()from limits。

回答by Remy Lebeau

#include <limits>

max_unsigned_int_size = std::numeric_limits<unsigned int>::max();