无法摆脱“这个十进制常量仅在 ISO C90 中是无符号的"；警告 [英] Can't get rid of "this decimal constant is unsigned only in ISO C90" warning

问题描述

我在我的哈希表实现中使用 FNV 哈希作为哈希算法，但我在这一行的问题标题中收到警告:

I'm using the FNV hash as a hashing algorithm on my Hash Table implementation but I'm getting the warning in the question title on this line:

unsigned hash = 2166136261;

我不明白为什么会这样，因为当我这样做时:

I don't understand why this is happening because when I do this:

printf("%u
", UINT_MAX);
printf("2166136261
");

我明白了:

4294967295
2166136261

这似乎在我的机器的限制之下......

Which seems to be under the limits of my machine...

为什么我会收到警告，我有什么方法可以摆脱它?

Why do I get the warning and what are my options to get rid of it?

推荐答案

unsigned hash = 2166136261u; // note the u.

您需要一个后缀 u 来表示这是一个无符号数.如果没有 u 后缀，它将是一个带符号的数字.自从

You need a suffix u to signify this is an unsigned number. Without the u suffix it will be a signed number. Since

2166136261 > 2³¹ - 1 = INT_MAX,

这个整数文字会有问题.

this integer literal will be problematic.

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