python中的printf：%号拼接字符串和format函数

Posted 2020-10-28 代码螺丝钉

在C语言中，我们使用printf("%s","hello")这种形式进行字符串的拼接

在python中，进行这样的拼接有两种实现方式，分别是%号拼接以及使用format函数，以下进行代码演示

%号拼接字符串

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 在python中是用%号可以进行字符串的拼接，这个跟print函数是无关的。以下进行举例

• 打印字符串

  msg = "i am %s,my blogs is %s" % ("CodeScrew","www.cnblogs.com/codescrew")
  print(msg)

• 打印浮点数

  msg = "i am %0.2f m" %1.785
  print(msg)  #打印结果为i am 1.78 m

  其中%号后面的.2表示保留2位小数

• 打印百分比

  msg = "it is %0.2f %%" % 99.852
  print(msg)  #打印结果为it is 99.85 %

• 使用键值对进行拼接

  msg = "i am %(name)s.my age is %(age)d" % ({"name":"CodeScrew","age":23})
  print(msg)  #打印结果为i am CodeScrew.my age is 23

format函数处理字符串

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 除了%号进行拼接，还可以使用字符串类的format函数，以下列举了常用的使用。

msg = "i am {},age is {}".format("CodeScrew",23)
print(msg)  #打印结果为i am CodeScrew,age is 23

msg = "i am {1},age is {0}".format("CodeScrew",23)
print(msg)  #打印结果为i am 23,age is CodeScrew

msg = "i am {name},age is {age}".format(name="CodeScrew",age=23)
print(msg)  #打印结果为i am CodeScrew,age is 23

msg = "i am {name},age is {age}".format(**{"name":"CodeScrew","age":23})
print(msg)  #打印结果为i am CodeScrew,age is 23

msg = "i am {:s},age is {:d}".format("CodeScrew",23)
print(msg)  #打印结果为i am CodeScrew,age is 23

msg = "i am {:s},age is {:d}".format(*["CodeScrew",23])
print(msg)  #打印结果为i am CodeScrew,age is 23

msg = "Numbers:{:b},{:o},{:d},{:x},{:X}".format(15,15,15,15,15)
print(msg)  #打印结果为Numbers:1111,17,15,f,F