[Python Notes] Formatted output (% usage)

1. Formatted output

1. Integer output

%o - oct octal
%d - dec decimal
%x - hex hex

usage:

>>> print('%o' % 20)
24
>>> print('%d' % 20)
20
>>> print('%x' % 20)
14

Incorrect usage:

>>> print('%o',20)
%o 20

2. Floating point output

(1) Formatted output
%f - retain six significant digits after the decimal point. Example: %.3f, 3 decimal places are
reserved %e - 6 significant digits after the decimal point are reserved, and the output is in exponential form. Example: %.3e, keep 3 decimal places, use scientific notation
%g - on the premise of guaranteeing six significant figures, use the decimal method, otherwise use the scientific notation method. Example: %.3g, keep 3 significant figures, use decimal or scientific notation

 >>> print('%f' % 1.11)  # 默认保留6位小数
 1.110000
 >>> print('%.1f' % 1.11)  # 取1位小数
 1.1
 >>> print('%e' % 1.11)  # 默认6位小数，用科学计数法
 1.110000e+00
 >>> print('%.3e' % 1.11)  # 取3位小数，用科学计数法
 1.110e+00
 >>> print('%g' % 1111.1111)  # 默认6位有效数字
 1111.11
 >>> print('%.7g' % 1111.1111)  # 取7位有效数字
 1111.111
 >>> print('%.2g' % 1111.1111)  # 取2位有效数字，自动转换为科学计数法
 1.1e+03

A more common usage is:

print("a/b="+str("%.2f\n" %(a/b))#一定要用str，不然会提示类型不同不能相加