最简单的例子是:

代码:

>>>分= 19.5分 >>> total = 22 >>>'正确答案:{:.2%}'.format(分数/总分) ｀

输出:正确答案:88.64%

如果你用这个来表示货币，并且还想用's来分隔值，你可以使用's

$ {:, .f2} .format (currency_value)。

例如:

Currency_value = 1234.50

$ {:，.f2}.format(currency_value)——> $ 1,234.50

下面是我不久前写的一段代码:

print(">在年底" + year_string + " total paid is \t$ {:，.2f}".format(total_paid))

> At the end of year   1  total paid is         $ 43,806.36
> At the end of year   2  total paid is         $ 87,612.72
> At the end of year   3  total paid is         $ 131,419.08
> At the end of year   4  total paid is         $ 175,225.44
> At the end of year   5  total paid is         $ 219,031.80   <-- Note .80 and not .8
> At the end of year   6  total paid is         $ 262,838.16
> At the end of year   7  total paid is         $ 306,644.52
> At the end of year   8  total paid is         $ 350,450.88
> At the end of year   9  total paid is         $ 394,257.24
> At the end of year  10  total paid is         $ 438,063.60   <-- Note .60 and not .6
> At the end of year  11  total paid is         $ 481,869.96
> At the end of year  12  total paid is         $ 525,676.32
> At the end of year  13  total paid is         $ 569,482.68
> At the end of year  14  total paid is         $ 613,289.04
> At the end of year  15  total paid is         $ 657,095.40   <-- Note .40 and not .4  
> At the end of year  16  total paid is         $ 700,901.76
> At the end of year  17  total paid is         $ 744,708.12
> At the end of year  18  total paid is         $ 788,514.48
> At the end of year  19  total paid is         $ 832,320.84
> At the end of year  20  total paid is         $ 876,127.20   <-- Note .20 and not .2

OP总是希望显示两个小数点后的位置，因此像所有其他答案所做的那样，显式地调用格式化函数是不够的。

正如其他人已经指出的那样，Decimal适用于货币。但是Decimal显示了所有的小数点。因此，重写它的显示格式化器:

class D(decimal.Decimal):
    def __str__(self):
        return f'{self:.2f}'  

用法:

>>> cash = D(300000.991)
>>> print(cash)
300000.99

简单。

编辑:

显示小数点后至少两位，但不截断有效数字:

class D(decimal.Decimal):
    def __str__(self):
        """Display at least two decimal places."""
        result = str(self)
        i = result.find('.')
        if i == -1:
             # No '.' in self. Pad with '.00'.
             result += '.00'
        elif len(result[i:]) == 2:
             # One digit after the decimal place. Pad with a '0'.
             result += '0'
        return result

我希望Python的未来版本将改进数字格式，以允许最小的小数位数。类似于Excel数字格式中的#符号。

这与你可能已经看到的解决方案是一样的，但是这样做会更清楚:

>>> num = 3.141592654

>>> print（f“Number： {num：.2f}”）

.format是一种可读性更好的处理变量格式化的方式:

'{:.{prec}f}'.format(26.034, prec=2)

是什么

print round(20.2564567 , 2)    >>>>>>>        20.25


print round(20.2564567 , 4)    >>>>>>>        20.2564