在C / C ++中使用INT_MAX和INT

In this article, we’ll take a look at using INT_MAX and INT_MIN in C/C++.

在本文中，我们将研究在C / C ++中使用INT_MAX和INT_MIN。

These are actually useful macros which represent the maximum and minimum integer values.

这些实际上是有用的宏，它们代表最大和最小整数值。

Let’s take a look at it, using some examples.

让我们使用一些示例来看看它。

使用INT_MAX和INT_MIN (Using INT_MAX and INT_MIN)

INT_MAX is a macro which represents the maximum integer value. Similarly, INT_MIN represents the minimum integer value.

INT_MAX是代表最大整数值的宏。同样，INT_MIN表示最小整数值。

These macros are defined in the header file <limits.h>, so you must include it.

这些宏在头文件<limits.h>中定义，因此您必须包括它。


#include <limits.h>INT_MAXINT_MIN

Note that any integer variable must lie between INT_MIN and INT_MAX.

请注意，任何整数变量都必须位于INT_MIN和INT_MAX之间。

Typically, integers are stored as 4 bytes (32 bits).

通常，整数存储为4个字节（32位）。

This means that in almost all machines, the maximum integer value will be 2^(31) – 1 = +2147483647.

这意味着在几乎所有计算机中，最大整数值为2 ^（31）– 1 = +2147483647。

The minimum integer value will be -(2^31) = -2147483648

最小整数值为-（2 ^ 31）= -2147483648

Let’s verify this, for our machine.

让我们为我们的机器验证一下。


#include <stdio.h>
#include <limits.h>int main() {printf("Maximum Integer Value: %d\n", INT_MAX);printf("Minimum Integer Value: %d\n", INT_MIN);return 0;
}

Output

输出量


Maximum Integer Value: 2147483647
Minimum Integer Value: -2147483648

Indeed, we get what we predict.

确实，我们得到了我们的预测。

Let’s now take another example, to correctly predict any integer overflow or underflow.

现在再举一个例子，正确预测任何整数上溢或下溢。


#include <stdio.h>
#include <limits.h>int main() {int value = 0;while (value >= 0) {// Check for overflowif (value == INT_MAX) {printf("value = %d. Possible overflow!\n", value);}value ++;}printf("Now, value = %d\n", value);value = 0;while (value <= 0) {// Check for underflowif (value == INT_MIN) {printf("value = %d. Possible underflow!\n", value);}value --;}printf("Now, value = %d\n", value);return 0;
}

Output

输出量


value = 2147483647. Possible overflow!
Now, value = -2147483648
value = -2147483648. Possible underflow!
Now, value = 2147483647

While this takes a good few seconds to run, this does indeed do what we expect.

虽然这需要花好几秒钟的时间，但确实可以达到我们的预期。

The integer will overflow to INT_MIN, and will underflow to INT_MAX.

整数将溢出到INT_MIN ，并将下溢到INT_MAX 。

This is useful to detect such jumps in the values.

这对于检测这些值的跳跃很有用。

为什么我们需要这些宏？ (Why do we need these macros?)

Often, for certain algorithms, it is sometimes necessary to initialize a variable as the lowest/highest value.

通常，对于某些算法，有时有必要将变量初始化为最低/最高值。

The number of bits of the datatype may differ based on the machine.

数据类型的位数可能会因计算机而异。

To make the usage of the maximum/minimum values be consistent, it would be convenient if everyone could use the same macros!

为了使最大值/最小值的用法保持一致，如果每个人都可以使用相同的宏，那将很方便！

This is exactly why these kinds of macros exist –

这正是存在此类宏的原因-

To spare you from remember the actual values为了让您免于记忆实际值
Have consistent programming patterns across all machines在所有机器上具有一致的编程模式
Very convenient to use使用非常方便

Hopefully, these reasons may convince you to use such kinds of macros whenever you build your own C/C++ library.

希望这些原因可以说服您在构建自己的C / C ++库时使用此类宏。

结论 (Conclusion)

In this article, we learned about using the INT_MAX and INT_MIN macros in C / C++.

在本文中，我们学习了有关在C / C ++中使用INT_MAX和INT_MIN宏的知识。

For similar content, do go through our tutorial section on C programming.

对于类似的内容，请阅读我们有关C编程的教程部分。

参考资料 (References)

cplusplus.com page on climitsclimits上的cplusplus.com 页面

翻译自: https://www.journaldev.com/41151/int-max-min-c-plus-plus