Python浮点舍入

Question

Trying to figure out the correct rounding technique:

v = float(input("Enter V: "))

print ("V is %.3f" % str(round(v,3)))

Where am I going wrong?

Answer 1

str(round(v,3)

is the problem here, just remove the str

you're changing into a string, which is wrong

Answer 2

Using str turns the float into a string. Remove the str :

print ("V is %.3f" % round(v, 3))

UPDATE
As Barnie suggested in a comment above: there's no need for rounding since you're printing using %.3f so you do even better:

print ("V is %.3f" % v)