Re: [問題] 關於作業七

[ric2k1 (Ric)]

※ 引述《Knossos ()》之銘言：
: ※ 引述《ric2k1 (Ric)》之銘言：
: : Yes.
: 既然size_t就是非負整數，那它跟unsigned有什麼差別？為什麼要用它？

Different architectures or platforms may have different difinitions on the

sizes of different data types. It's difficult to set a single standard for

everyone to follow. Therefore, in ISO/IEC 9899:1990, they left the definition

of the short int, the int, the long int, and the pointer deliberately vague

to avoid artificially constraining hardware architectures.


The only constraint:

sizeof(char) <= sizeof(short) <= sizeof(int) <= sizeof(long) <= sizeof(size_t)


Usually sizeof(size_t) is defined as the same as sizeof(void *) to match

the size of pointer variable (i.e number of bytes to store a memory address).

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推 Knossos:sizeof(void *)不是4嗎？怎麼會比sizeof(long)大？
→ ric2k1:sizeof(long) = sizeof(long int) = 4
→ ric2k1:sizeof(long long) 才 = 8...
推 timrau:我查到的是sizeof(long) <= sizeof(long long)耶....
→ ric2k1:其實 int 分為 short int and long int, 一般在用的 int
→ ric2k1:其實就是 long int... 而 short int 就是 short.
推 timrau:For example in Turbo C++, sizeof(long)=4 while
→ timrau:sizeof(size_t)=2
→ ric2k1:說實在的 Turbo C++ 這樣蠻奇怪的, 雖然我後來查到
→ ric2k1:ISO/IEC 9899:1990 was withdrawn... 不過 size_t 應該通常
→ ric2k1:是用來存 number of objects (如 array size),
→ ric2k1:so it must be big enough to hold the "maximum number
→ ric2k1:of objects" that can be hold. 2^16 = 65536 也太少了吧?
推 lionel20002:dev-C++sizeof(size_t)是4 compiler有差??