Python格式化字符串：%、format、f-string

目前Python格式化字符串的方式有三种：

1. % 

2.format

3.f-string

% 格式化常用方法：

# % 格式化字符串 
s1 = 'name is %s' % ('zhangsan')
# >>> name is zhangsan

# % 格式化整数
s2 = 'age is %d' % (12)
# >>> age is 12

# % 格式化整数，指定位数，用0填充
s3 = 'today is %02d' % (8)
# >>> today is 08

# % 格式化浮点数，默认保留6位小数
s4 = 'PI = %f' % (3.1415)
# >>> PI = 3.141500

# % 格式化浮点数，保留2位小数
s5 = 'PI = %.2f' % (3.1415)
# >>> PI = 3.14

# % 格式化浮点数，不带小数
s6 = 'PI = %.0f' % (3.1415)
# >>> PI = 3

format 格式化常用方法：

# format 格式化字符串 
s1 = 'name is {}'.format('zhangsan')
# >>> name is zhangsan

# format 格式化整数
s2 = 'age is {}'.format(12)
# >>> age is 12

# format 格式化整数，指定位数，用0填充
s3 = 'today is {:0>3d}'.format(8)
# >>> today is 008

# format 格式化整数，以逗号分隔
s4 = 'number is {:,}'.format(123456789)
# >>> number is 123,456,789

# format 格式化整数，指数记法
s5 = 'number is {:.2e}'.format(123456789)
# >>> number is 1.23e+08

# format 格式化浮点数
s6 = 'PI = {}'.format(3.1415)
# >>> PI = 3.1415

# format 格式化浮点数，保留2位小数
s7 = 'PI = {:.2f}'.format(3.1415)
# >>> PI = 3.14

# format 格式化浮点数，带符号保留两位小数
s8 = 'PI = {:+.2f}'.format(-3.1415)
# >>> PI = -3.14

# format 格式化浮点数，百分比显示
s9 = 'number is {:.2%}'.format(3.1415)
# >>> number is 314.15%

# format 格式化浮点数，不带小数
s10 = 'PI = {:.0f}'.format(3.1415)
# >>> PI = 3

f-string 格式化常用方法：

data1 = 'zhangsan'
data2 = 123456789
data3 = 3.1415

# f 格式化字符串 
s1 = f'name is {data1}'
# >>> name is zhangsan

# f 格式化整数
s2 = f'number is {data2}'
# >>> number is 12

# f 格式化整数，指定位数，用0填充
s3 = f'number is {data2:010d}'
# >>> number is 0123456789

# f 格式化浮点数
s4 = f'PI = {data3}'
# >>> PI = 3.1415

# f 格式化浮点数，保留2位小数
s5 = f'PI = {data3:.2f}'
# >>> PI = 3.14

# f 格式化浮点数，不带小数
s6 = f'PI = {data3:.0f}'
# >>> PI = 3