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I've been wondering this for a long time since I've never had "formal" education on computer science (I'm in highschool), so please excuse my ignorance on the subject.
On a platform that supports the three types of integers listed in the title, which one's better and why? (I know that every kind of int has a different length in memory, but I'm not sure what that means or how it affects performance or, from a developer's view point, which one has more advantages over the other).
Thank you in advance for your help.
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A 32-bit system can access 232 different memory addresses, i.e 4 GB of RAM or physical memory ideally, it can access more than 4 GB of RAM also. A 64-bit system can access 264 different memory addresses, i.e actually 18-Quintillion bytes of RAM.
Answer: In computing, 32-bit and 64-bit are two different types of processors. The bit number (usually 8, 16, 32, or 64) refers to how much memory a processor can access from the CPU register. Most computers made in the 1990s and early 200s were 32-bit machines.
int is 32 bits in size. long , ptr , and off_t are all 64 bits (8 bytes) in size.
int64. A 64-bit signed integer. It has a minimum value of -9,223,372,036,854,775,808 and a maximum value of 9,223,372,036,854,775,807 (inclusive). string. uint64.
"Better" is a subjective term, but some integers are more performant on certain platforms.
For example, in a 32-bit computer (referenced by terms like 32-bit platform and Win32) the CPU is optimized to handle a 32-bit value at a time, and the 32 refers to the number of bits that the CPU can consume or produce in a single cycle. (This is a really simplistic explanation, but it gets the general idea across).
In a 64-bit computer (most recent AMD and Intel processors fall into this category), the CPU is optimized to handle 64-bit values at a time.
So, on a 32-bit platform, a 16-bit integer loaded into a 32-bit address would need to have 16 bits zeroed out so that the CPU could operate on it; a 32-bit integer would be immediately usable without any alteration, and a 64-bit integer would need to be operated on in two or more CPU cycles (once for the low 32-bits, and then again for the high 32-bits).
Conversely, on a 64-bit platform, 16-bit integers would need to have 48 bits zeroed, 32-bit integers would need to have 32 bits zeroed, and 64-bit integers could be operated on immediately.
Each platform and CPU has a 'native' bit-ness (like 32 or 64), and this usually limits some of the other resources that can be accessed by that CPU (for example, the 3GB/4GB memory limitation of 32-bit processors). The 80386 processor family (and later x86) processors made 32-bit the norm, but now companies like AMD and then Intel are currently making 64-bit the norm.
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To answer your first question, the usage of a 16 bit vs a 32 bit vs a 64 bit integer depends on the context that it is used. Therefore, you really can't say one is better over the other, per say. However, depending on a situation, using one over another is preferable. Consider this example. Let's say you have a database with 10 million users and you want to store the year they were born. If you create a field in your database with a 64 bit integer then you have exhausted 80 megabytes of your storage; whereas, if you were to use a 16 bit field, only 20 megabytes of your storage will get used. You can use a 16 bit field here because the year people are born is smaller than the largest 16 bit number. In other words 1980, 1990, 1991 < 65535, assuming your field is unsigned. All in all, it depends on the context. I hope this helps.
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