为什么小数点被忽略？

Question

所以我正在做这个小的复利计算器，我有一个问题，我不知道怎么解决！出于某种原因，python似乎并不关心数字中有小数这一事实。例如，如果一个数字在代码中是12588.01，那么它将被视为12588。任何帮助都是非常感谢的！

p = 12588.01  #principle
r = 4.9  #rate as percent
t = 20  #time

# math
r = r / 100

# math and output
for i in range(t):
    interest = p * r
    #interest = round(interest, 2)

    #generates the spaces between the time and numbers
    timeSpace = 5 - len(str(i+1))
    timeSpace = " " * int(timeSpace)

    #generates the spaces used in the first part of the output
    firstSpace = 10 - len(str(round(p)))
    firstSpace = " " * int(firstSpace)

    #generated the space used in the second part of the output
    secondSpace = 10 - len(str(round(interest)))
    secondSpace = " " * int(secondSpace)

    #output

    #print("Year: %d%s|%d%s|%d%s|%d" % (i+1, timeSpace, round(p, 2), firstSpace, interest, secondSpace, round(interest+p, 2)))
    print("Year: %d%s|%d%s|%d%s|%d" % (i+1, timeSpace, float(p), firstSpace, float(interest), secondSpace, float(interest+p)))

    p = p + interest
    #p = round(p, 2)

这个计算器正在使用货币，因此应该循环，但是在我尝试修复代码的过程中，我将它们注释掉了。

Answer 1

您使用%d打印浮点数，这是用于整数的。使用%.2f将浮点数打印到小数点后两位。

Answer 2

使用具有正确格式的字符串格式：

p = 12588.01  #principle
r = 4.9  #rate as percent
t = 20  #time

r /= 100

for i in range(t):
    interest = p * r
    print(f"Year: {i+1:<5d}|{p:<10.2f}|{interest:<10.2f}|{interest+p:.2f}")
    p += interest