python字符串调用举例

以如下打印为例:

my name is tom and my age is 12

方式一:字符串格式化表达式

name = 'tom'
age = 12

print("my name is %s and my age is %d" %(name,age))

value为一个元组

says = "my name is %s and my age is %s"
value =('tom', 12)
says%value

方式二:字符串格式化方法调用

name = 'tom'
age = 12

print("my name is {name} and my age is {age}".format(name='tom',age=12))

使用索引,注意下面例子中format两个参数的赋值顺序:

print("my name is {1} and my age is {0}".format(12,'tom'))

也可以省略索引值

print("my name is {} and my age is {}".format('tom',12))

省略索引值时,format后可以是形参

name = 'tom'
age = 12

print("my name is {} and my age is {}".format(name,age))

注意以下调用反而会引起错误

name = 'tom'
age = 12

print("my name is {name} and my age is {age}".format(name,age))

Traceback (most recent call last):
  File "<pyshell#586>", line 1, in <module>
    print("my name is {name} and my age is {age}".format(name,age))
KeyError: 'name'

方式三:f字符串

在Python 3.6中，如果变量与替换字段同名，还可使用一种简写。在这种情况下，可使用f字符串——在字符串前面加上f

name = 'tom'
age = 12

print(f"my name is {name} and my age is {age}")

方式四:使用加号拼接

name = 'tom'
age = 12

print("my name is " + name + " and my age is " + str(age))