python有哪些字符串查找类方法

s = "bird,fish,monkey,rabbit"

s.find('fish') #5

s.rfind('b') #20

s.find('tiger') #-1

s = "bird,fish,monkey,rabbit"

s.index('bird') #0

s.rindex('i') #21

s.index('tiger') #指定字符串不存在 substring not found

s = "bird,fish,monkey,rabbit"

s.count('bird') # 1

s.count('b') # 3

s.count('tiger') #0