Common data type ranges
From Maths
TODO: This is just some notes for me to reference at the moment, please only use these IF YOU KNOW THEY APPLY - there are various C conventions...
Signed integers - 2's complement
- In general, given n bits, the range of x (an n-bit signed two's complement integer) is:
- −2n−1≤x≤2n−1−1, which we may write as a closed interval of the integers, x∈[−2n−1, 2n−1−1]
| Bits | Range (inclusive) | Comment | |||
|---|---|---|---|---|---|
| Signed | Unsigned | ||||
| Low | High | Low | High | ||
| 8 | -128 | 127 | 0 | 255 | |
| 16 | -32,768 | 32,767 | 0 | 65,365 | Often associated with older spreadsheet software, only supporting rows from 1 to 65,536. Note the offset[Note 1]. |
| 24 | -8,388,608 | 8,388,607 | 0 | 16,777,215 | Relevant for float - per standard. |
| 32 | -2,147,483,648 | 2,147,483,647 | 0 | 4,294,967,295 | Notice that 2,147,483,647 is about 68.05 years[Note 2], and 1970+68=2038 - see 2038 problem |
| 64 | -9,223,372,036,854,775,808 | 9,223,372,036,854,775,807 | 0 | 18,446,744,073,709,551,615 | 9.2 billion trillion, 18.4 billion trillion using 10^3 increments. |
TODO: Notice the lowest digit of each column is the same. Why?
Notes
- Jump up ↑ Internally for rows they'd have used shorts for the job, adding one to the displayed row number as spreadsheets have no row 0.
- Jump up ↑ Calculation:
- A:=231−160∗60∗24∗365.25≈68.04965039 which is 68 years and (A−68)∗365.25≈18.135, so:
