Python之路第三篇:Python基础之杂货铺

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字符串格式化

Python的字符串格式化有两种方式:百分号方式、format方式

百分号的方式相对来说比较老,而format方式则是比较先进的方式,企图替换古老的方式,目前两者并存。

1、百分号方式

%[(name)][flags][width].[precision]typecode
● (name)      可选,用于选择指定的key
●  flags          可选,可供选择的值有:
       ●  +       右对齐;正数前加正好,负数前加负号;
       ●   -        左对齐;正数前无符号,负数前加负号;
       ●  空格    右对齐;正数前加空格,负数前加负号;
       ●  0        右对齐;正数前无符号,负数前加负号;用0填充空白处
●  width         可选,占有宽度
●  .precision   可选,小数点后保留的位数
●  typecode    必选
        ● s,获取传入对象的__str__方法的返回值,并将其格式化到指定位置
        ● r,获取传入对象的__repr__方法的返回值,并将其格式化到指定位置
        ● c,整数:将数字转换成其unicode对应的值,10进制范围为 0 <= i <= 1114111(py27则只支持0-255);字符:将字符添加到指定位置
        ● o,将整数转换成 八  进制表示,并将其格式化到指定位置
        ● x,将整数转换成十六进制表示,并将其格式化到指定位置
        ● d,将整数、浮点数转换成 十 进制表示,并将其格式化到指定位置
        ● e,将整数、浮点数转换成科学计数法,并将其格式化到指定位置(小写e)
        ● E,将整数、浮点数转换成科学计数法,并将其格式化到指定位置(大写E)
        ● f ,将整数、浮点数转换成浮点数表示,并将其格式化到指定位置(默认保留小数点后6位)
        ● F   同上
        ● g,自动调整将整数、浮点数转换成  浮点型或科学计数法表示(超过6位数用科学计数法),并将其格式化到指定位置(如果是科学计数则是e;)
        ● G,自动调整为整数、浮点数转换成 浮点型或科学计数法表示(超过6位数用科学计数法),并将其格式化到指定位置(如果是科学计数则是E;)
        ● % ,当字符串中存在格式化标志时,需要用%%表示一个百分号
注:Python中百分号格式化是不存在将整数转换成二进制表示的方式
      

 常用格式化:

msg = "i am %s my hobbby is %s" %(william, basketball)
print(msg)
输出结果:
i am william my hobbby is basketball

msg = i am %s ,age %s %(william,18)
print(msg)
输出结果:
i am william ,age 18

msg = i am %(name)s age %(age)d % {name: william, age: 19}
print(msg)
输出结果:
i am william age 19

#打印浮点数
tpl = "percent %.2f" % 99.97623445463344
print(tpl)
输出结果:
percent 99.98

#打印百分比
tpl = "percent %.2f %%" % 99.97623445463344
print(tpl)
输出结果:
percent 99.98 %

msg = i am %(name)+60s my hobby is basketball. % {name: william}
print(msg)
输出结果:
i am                                                      william my hobby is basketball.

msg = i am \033[43;1m%(name)+60s\033[0m my hobby is basketball. % {name: william}
print(msg)
输出结果:
i am                                                      william my hobby is basketball.

print(root, x, 0, 0,sep=:)
输出结果:
root:x:0:0

 

 2、Format方式

表达格式:

[fill]align][sign][#][0][width][,][.precision][type]

常用格式化:

 

msg = i am {},age {}, {}.format(zhurui, 24, william)
print(msg)
输出结果:
i am zhurui,age 24, william

msg = i am {},age {}, {}.format(*[zhurui, 24, william])
print(msg)
输出结果:
i am zhurui,age 24, william

msg = i am {0}, age {1},really {0}.format(zhurui,24)
print(msg)
输出结果:
i am zhurui, age 24,really zhurui

msg = i am {0}, age {1},really {0}.format(*[zhurui,24])
print(msg)
输出结果:
i am zhurui, age 24,really zhurui

msg = i am {name}, age {age},really {name}.format(name=william, age=24)
print(msg)
输出结果:
i am william, age 24,really william

msg = i am {name}, age {age},really {name}.format(**{name: william, age: 24}) #format如果用字典的话,前面加**
print(msg)
输出结果:
i am william, age 24,really william

msg = i am{0[0]}, age {0[1]}, really {0[2]}.format([1, 2, 3], [11, 22, 33])
print(msg)
输出结果:
i am1, age 2, really 3

msg = i am {:s}, age {:d}, money {:f}.format(william,24,89.3432)
print(msg)
输出结果:
i am william, age 24, money 89.343200

msg = i am {:s},age {:d}.format(*[william, 24])
print(msg)
输出结果:
i am william,age 24

msg = i am {name:s},age {age:d}.format(**{name: william,age: 24})
print(msg)
输出结果:
i am william,age 24

msg = "numbers: {:b},{:o},{:d},{:x},{:X}, {:%}".format(15, 15, 15, 15, 15, 15.87623, 2)
print(msg)
输出结果:
numbers: 1111,17,15,f,F, 1587.623000%

msg = "numbers: {:b},{:o},{:d},{:x},{:X}, {:%}".format(15, 15, 15, 15, 15, 15.87623, 2)
输出结果:
numbers: 1111,17,15,f,F, 1587.623000%

msg = "numbers: {0:b},{0:o},{0:d},{0:x},{0:X}, {0:%}".format(15)
print(msg)
输出结果:
numbers: 1111,17,15,f,F, 1500.000000%

msg = "numbers: {num:b},{num:o},{num:d},{num:x},{num:X}, {num:%}".format(num=15)
print(msg)
输出结果:
numbers: 1111,17,15,f,F, 1500.000000%

 

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