What are the hidden holes in Python? On the rounding of round function in Python

After looking around, Gao Zan replied , Nobody even mentioned this .

Everybody knows ,round() It is used for rounding .

however , There are special circumstances ：

​

Have you found any problems ？

• 7.55 Keep one decimal place , Rounding , Should have 7.6, But I got 7.5

• 1.315 Keep two decimal places , Rounding , Should the 1.32, But I got 1.31

because ,Python It does not follow rounding , It is “ Round to the nearest pair ”

Python Official documents ：

round Introduce ： Built in functions — Python 3.10.5 file

The controversy and limitation of floating point arithmetic ：15. Floating point arithmetic ： Disputes and restrictions - Python 3.10.5 file

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So , I wrote a special function , Fix this problem （ If it counts as a problem ）：

def new_round(v_value, ndigits=1):
"""
Repair python The question of rounding
:param ndigits: Keep a few decimal places
:param v_value: Enter the value
:return: Output value
"""
f = int(v_value) % 10
if f <= 4:
v_value = (int(v_value) // 10) / 10
else:
v_value = (int(v_value) // 10 + 1) / 10
print(v_value)
return v_value

Whether it counts or not Python Of bug, But you must know this .

Don't let your program , Because of it , Calculate the wrong result , He didn't know it ！

By then , If not python Of bug, It's also your program bug 了 ！！

Python Is there any unknown pit ？ - You know | Horse brother python say

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