格式化输出

目录

• 1 格式化输出
  • 1.1 占位符（%s）
  • 1.2 format 格式化
  • 1.3 f-string格式化

1 格式化输出

在之前的课程中，有顺带的提过格式化输出，如下按照某某某's weight is … and height is …格式进行输出

name = 'Hades'
weight = 125
height = 168

print(name + "'s weight is " + str(weight) + ' and height is ' + str(height))

Hades's weight is 125 and height is 168

这看起来还是可以的，但是在打印的时候一不小心就会报错，因为weight和height都是数字，不能与字符串进行相加，所以还需要进行数据类型转换，将int转换成str，这样就多了很多会出错的操作，很不方便。
这就体现出如下三种格式化输出的优势了。

1.1 占位符（%s）

使用%s来先进行占位置，然后在进行补全，具体格式为print("%s's weight is %s and height is %s"%(name,weight,height))

name = 'Hades'
weight = 125
height = 168

print("%s's weight is %s and height is %s"%(name,weight,height))

Hades's weight is 125 and height is 168

注意：有几个占位符就必须传几个数值，不然会报错，如下：

1. 占位符多了，报错

name = 'Hades'
weight = 125
height = 168

print("%s's weight is %s and height is %s %s"%(name,weight,height))

---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

<ipython-input-11-4195a55b7081> in <module>
      3 height = 168
      4 
----> 5 print("%s's weight is %s and height is %s %s"%(name,weight,height))


TypeError: not enough arguments for format string

2. 传递的数据多了，报错

name = 'Hades'
weight = 125
height = 168

print("%s's weight is %s and height is %s"%(name,weight,height,height))

---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

<ipython-input-12-6bfa2e1aafe5> in <module>
      3 height = 168
      4 
----> 5 print("%s's weight is %s and height is %s"%(name,weight,height,height))


TypeError: not all arguments converted during string formatting

1.2 format 格式化

format格式化也是一种格式化输出，具体格式为('{} gfysr{} +1234567 {}'.format(a,b c))
相较于占位符和f-string这两种，format比较繁琐，代码量比较大，不信我们接下来看：

name = 'Hades'
weight = 125
height = 168

print("{}'s weight is {} and height is {}".format(name,weight,height))

Hades's weight is 125 and height is 168

pai = 3.1415926

print('{:.0f}'.format(pai))    # 格式化输出小数点后几位数，不够的用0添加
print('{:.4f}'.format(pai))
print('{:.10f}'.format(pai))

3
3.1416
3.1415926000

1.3 f-string格式化

f-string格式化输出比较方便，使用起来也很简单，具体格式为f"{name}'s weight is {weight} and height is {height}"

name = 'Hades'
weight = 125
height = 168

print(f"{name}'s weight is {weight} and height is {height}")

Hades's weight is 125 and height is 168

name = 'Hades'
weight = 125
height = 168

print(F'{name}’s weight is {weight} and height is {height}')    # f/F都可以，''/""也是一样的

Hades’s weight is 125 and height is 168

pai = 3.1415926

print(f'{pai:.2f}')    # 同样的，f-string也可以格式化输出小数点后几位数，不够的用0添加
print(f'{pai:.5f}')
print(f'{pai:.15f}')

3.14
3.14159
3.141592600000000