Python 字符串格式化

1.用%s来表示

s = "welcome %s to login %s"%("alex","china")
print (s)

s = "welcome %(name)s to login %(city)s"%{"name":"alex","city":"wuhan"}
print (s)

s = "%10s is %+10d years old"%("alex",-10)
print (s)

      alex is        -10 years old
解释：第一个字符串占10个字符，右对齐，第二个也占10个字符，右对齐，+号正数前面加+，负数前面加-。

s = "The pi is %.4f"%(3.1415926)
print (s)
The pi is 3.1416
或者是下面的写法

s = "The pi is %(p).4f"%{"p":3.1415926}

s = "The pi is ====%c=====%x======%o"%(65,15,15)
print (s)
The pi is ====A=====f======17

s = "alex %% %%"
print (s)

s1 = "alex %s %%%%"%("SB")
print (s1)

　输出：

  alex %% %%
  alex SB %%   #一旦前面出现过%占位符，后面只能用%%表示一个%

2.用format格式化

s = "----->{0}------>{1}------>{0}".format("alex",10)
print (s)

----->alex------>10------>alex

s = "----->{name:s}------>{age:d}------>{name:s}".format(name="alex",age=10)
print (s)
----->alex------>10------>alex

s = "-----{:9^20s}=====".format("alex")
print (s)
-----99999999alex99999999=====
解释：字符串宽度为20，居中放置，不足的部分用9来填充

s2 = "======{:*<20s}======{:+d}======{:#b}".format('alex',123,15)
print (s2)
======alex****************======+123======0b1111
解释：#号只是给b,o,x前面加上0b,0o,0x的符号

s3 = "{:.2%}".format(0.234567)
print (s3)
23.46%

s = "{} is {} years old".format("alex",18)
print (s)

s1 = "{} is {} years old".format(*["alex",18])
print (s1)

s2 = "{name} is {age} years old".format(**{"name":"alex","age":18})
print (s2)