python如何使用变量_python 如何引用变量

在字符串中引入变量有三种方法：

1、+ 连字符name = 'zhangsan'

print('my name is '+name)

结果为my name is zhangsan

2、% 字符name = 'zhangsan'

age = 25

price = 4500.225

print('my name is %s'%(name))

print('i am %d'%(age)+' years old')

print('my price is %f'%(price))

#保留指定位数小数(四舍五入)

print('my price is %.2f'%(price))

结果为my name is zhangsan

i am 25 years old

my price is 4500.225000

my price is 4500.23

3、format()函数

对于变量较多的情况，使用'+'或者'%'相对比较麻烦，这种情况下可以使用format函数name = 'zhangsan'

age = 25

price = 4500.225

info = 'my name is {my_name},i am {my_age} years old,my price is {my_price}'\

.format(my_name=name,my_age=age,my_price=price)

print(info)

结果为：my name is zhangsan,i am 25 years old,my price is 4500.225