变量大小是否依赖于语言机器实现意味着什么？

Question

Hope this is not confusing, but what I mean is why we say for instance that a long int 's size in C is machine implementation dépendent.

Does it mean the size is different for ARM processor, x86 processor, or PPC or ...?

Answer 1

It means that the compiler is free to pick any size that it think is appropriate, within the bounds given. (The long int type is defined as having at least a range that corresponds to a 32 bit number.)

Generally it means that different sizes are used for different platforms, depending on the machine word of the processor. Different compilers could even use different sizes for the same platform, and theoretically the same compiler could use different sizes for the same platform in different situations.

Answer 2

"does it mean the size is different for ARM processor , x86 processor , or PPC ..."

In short: Yes.