python的占位符

什么是占位符？

• 占位符：如其名，占据一个固定的位置；用于放置变量，在句中应用变量

三种常用的占位符

%占位符

需要%后区分变量类型

• 常见的占位符有：
  • %d 整数
  • %f 浮点数
  • %s 字符串
  • %x 十六进制整数

tpl = "i am %s" % "alex"
 
tpl = "i am %s age %d" % ("alex", 18)
 
tpl = "i am %(name)s age %(age)d" % {"name": "alex", "age": 18}
 
tpl = "percent %.2f" % 99.97623
 
tpl = "i am %(pp).2f" % {"pp": 123.425556, }
 
tpl = "i am %.2f %%" % {"pp": 123.425556, }

{} .format 占位符

｛｝中的数字需要是元组的下标

name = 'zhangsan'

sex = 'boy'

print('my name is {0} , my sex is {1} and his name is wangming ,his sex is {1}'.format(name,sex))

f'{}' 占位符

精确匹配

name = 'zhangsan'

sex = 'boy'

print(f'my name is {name} and my sex is {sex}')