Float

Coercing to Integers

Float → Integer (data loss)

ex: 10.4, 10.5, 10.6, 10.0001, 10.9999→ 10? 11？？

method : truncation, floor, ceiling, rounding

Truncation

無條件捨去(ignores everything after the decimal point)

import math
math.trunc(10.4) # 10
math.trunc(10.5) # 10
math.trunc(10.6) # 10

math.trunc(-10.4) # -10
math.trunc(-10.5) # -10
math.trunc(-10.6) # -10

• The Python int constructor will accept a float → uses truncation when casting the float to an int

# The int constructor uses truncation when a float is passed in:
int(10.4) # 10
int(10.5) # 10
int(10.6) # 10

int(-10.4) # -10
int(-10.5) # -10
int(-10.6) # -10

Floor

下取整(the floor of a number is the largest integer less than (or equal to) the number)

• 對正數來說, floor 與 truncation 是一樣的, 負數則否
• floor division: //, mod operation: n = d * (n // d) + (n % d)
• a // b = floor(a/b)