Python內置函數(33)——int

英文文檔：

class int(x=0) class int(x, base=10)

Return an integer object constructed from a number or string x, or return 0 if no arguments are given. If x is a number, return x.__int__(). For floating point numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in radix base. Optionally, the literal can be preceded by + or - (with no space in between) and surrounded by whitespace. A base-n literal consists of the digits 0 to n-1, with a to z (or A to Z) having values 10 to 35. The default base is 10. The allowed values are 0 and 2-36. Base-2, -8, and -16 literals can be optionally prefixed with 0b/0B, 0o/0O, or 0x/0X, as with integer literals in code. Base 0 means to interpret exactly as a code literal, so that the actual base is 2, 8, 10, or 16, and so that int('010', 0) is not legal, while int('010') is, as well as int('010', 8).

 

說明：

　　1. 不傳入參數時，得到結果0。

>>> int()
0

　　2. 傳入數值時，調用其__int__()方法，浮點數將向下取整。

>>> int(3)
3
>>> int(3.6)
3

　　3. 傳入字符串時，默認以10進制進行轉換。

>>> int('36')
36

>>> int('3.6')
Traceback (most recent call last):
  File "<pyshell#2>", line 1, in <module>
    int('3.6')
ValueError: invalid literal for int() with base 10: '3.6'

　　4. 字符串中允許包含"+"、"-"號，但是加減號與數值間不能有空格，數值后、符號前可出現空格。

>>> int('+36')
36
>>> int('-36')
-36
>>> int('   -36        ')
-36
>>> int(' - 36        ')
Traceback (most recent call last):
  File "<pyshell#7>", line 1, in <module>
    int(' - 36        ')
ValueError: invalid literal for int() with base 10: ' - 36   

　　5. 傳入字符串，並指定了進制，則按對應進制將字符串轉換成10進制整數。

>>> int('01',2)
1
>>> int('02',3)
2
>>> int('07',8)
7
>>> int('0f',16)
15