python 如何引用变量

name = 'zhangsan'

print('my name is '+name)

my name is zhangsan

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))

my name is zhangsan 

i am 25 years old 

my price is 4500.225000 

my price is 4500.23

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)

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