数组索引类型 [英] array index type
问题描述
什么类型可以/应该用作数组索引？
例如。我可以使用unsigned long吗？或者应该是size_t？
例如：
int sum（int * a，index_t n）{
int s = 0;
index_t i;
for（i = 0; i< n; ++ i）s + = a [i ];
返回s;
}
what type can/should be used as array index?
eg. can i use unsigned long? or should it be size_t?
example:
int sum(int *a, index_t n) {
int s = 0;
index_t i;
for (i = 0; i < n; ++i) s += a[i];
return s;
}
推荐答案
Szabolcs Nagy写道：
Szabolcs Nagy wrote:
什么类型可以/应该用作数组索引？
what type can/should be used as array index?
好的 - 前往沙坑。我可以看到圣战即将到来......
OK - head for the bunkers. I can see holy war coming...
eg。我可以使用unsigned long吗？或者应该是size_t？
例如：
int sum（int * a，index_t n）{
int s = 0;
index_t i;
for（i = 0; i< n; ++ i）s + = a [i ];
返回s;
}
eg. can i use unsigned long? or should it be size_t?
example:
int sum(int *a, index_t n) {
int s = 0;
index_t i;
for (i = 0; i < n; ++i) s += a[i];
return s;
}
我只会尝试回答可以 ;你的问题的一部分...
当我读到它时，C语言规范只声明
索引/下标必须是整数类型 - 大小类型，存在或
没有指定标志。
在此基础上，如果您的申请要求无签名长期
index / subscript，然后继续使用它。
我肯定有人会很快告诉你应该是什么类型
使用....
I''ll only try to answer the "can" part of your question...
As I read it, the C language specification states only that the
index/subscript must be of integer type - size of the type, presence or
absence of sign is not specified.
On that basis, if your application calls for unsigned long as
index/subscript, then go ahead and use it.
I''m sure someone will be along shortly to tell you what type should be
used....
Szabolcs Nagy写道：
Szabolcs Nagy wrote:
什么类型可以/应该用作数组指数？
例如。我可以使用unsigned long吗？或者应该是size_t？
例如：
int sum（int * a，index_t n）{
int s = 0;
index_t i;
for（i = 0; i< n; ++ i）s + = a [i ];
返回s;
}
what type can/should be used as array index?
eg. can i use unsigned long? or should it be size_t?
example:
int sum(int *a, index_t n) {
int s = 0;
index_t i;
for (i = 0; i < n; ++i) s += a[i];
return s;
}
虽然无符号类型应该有效，但可能需要做因此，按照C标准，它们可能会产生比未签名的
类型更多的开销。 unsigned long可能比其他
的可能性引发更多的可移植性问题。
While unsigned types should work, and are probably required to do so by
the C standard, they may incur significantly more overhead than unsigned
types. unsigned long probably incurs more portability issues than other
possibilities.
Tim Prince写道：
Tim Prince wrote:
虽然无符号类型应该可以使用，并且可能需要按照C标准来执行此操作，但它们可能会产生比未签名更多的开销。
类型。
While unsigned types should work, and are probably required to do so by
the C standard, they may incur significantly more overhead than unsigned
types.
签名还是未签名？
为什么会有开销？
感谢您的回答
signed or unsigned?
why is there overhead?
thanks for the answer
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