Given an integer, write an algorithm to convert this number to a hexadecimal number. For negative integer, we usually use complement arithmetic method.
note:
HEX All letters (af) must be lowercase.
Hex string can not contain excess leading zeros. If the number to be transformed is 0, then a single character '0' is represented; other cases, the hexadecimal character string will not be the first character 0.
To ensure that a given number in the range of 32-bit signed integer.
Not use any digital library provided by a method of direct conversion or hexadecimal format.
Example 1:
Input:
26
Output:
". 1A"
Example 2:
Input:
-1
Output:
"ffffffff"
[Notes] The core idea of using a bit operation, each 4 bits, corresponding to a hexadecimal number.
- Use
0xf(00 ... 01111b) to obtainnuma low of four. >>Arithmetic displacement, wherein a positive number of 0 up right left, right left S.1 negative.- Displacement calculation does not guarantee
num==0, required to ensure that 32-bit int (corresponding to hexadecimal 8 or less).
Use string directly string concatenation ....
string toHex(int num) {
if (num == 0) return "0"; string hex = "0123456789abcdef", ans = ""; while(num && ans.size() < 8){ ans = hex[num & 0xf] + ans; num >>= 4; } return ans; }