Python Note 006--function

Function basics

Count the number of characters in a string

1 def countsubstring (s,ch): #s和ch为形参2C=03I=04      whilei<Len (s):5         ifs[i]==Ch:6c + =17i + =18 print (c)9Str='WUJIADONGJIANGRUISUIRSUIUIGJSJSIUISLDJSJEUIUI'Tenm= ' I ' OneCountsubstring (s,m) #调用函数传入的参数str和m为实参

Count Sub-string sub-number

1 def countsubstring (s,sub):2C=03I=04      whileI<=len (s)-Len (sub):5         ifS[i:i+len (sub)]==Sub:6c + =17# Print (s[i:i+len (sub)])8i + =19 print (c)TenStr='WUJIADONGJIANGRUISUIRSUIUIGJSJSIUISLDJSJEUIUI' One  ACountsubstring (str,'UI')

1 def myfind (s,sub):2I=03      whileI<=len (s)-Len (sub):4         ifS[i:i+len (sub)]==Sub:5 print (i)6              Break7i + =18     Else:9Print'-1')Ten  OneStr='Wujiadong' Asub=' on' -Myfind (Str,sub)

Find the maximum value

1li=[111,2,3,7,9, the,98, at, $]2 def Myfindmax (M):3I=04max=li[0]5      whilei<Len (LI):6         ifmax<Li[i]:7max=Li[i]8 9i + =1Ten print (max) OneMyfindmax (LI)

Find the second largest value

#这种情况两个最大都相等时是错误的
1li=[111,222,333,7,9,765,98, at, $]2 def max2 (t):3max1=t[0]4max2=t[0]5      forXinchT:6         ifX >Max1:7Max2=Max18max1=x9         Else:Ten           ifX >MAX2: #这里添加上条件x! =max1 can be avoided OneMax2=x APrint'Max1', Max1) -Print'Max2', MAX2) -Max2 (LI)

Delete a value

#有bug, there are duplicate values that cannot be deleted

1li=[1,2,3,4,5,6,7,8,9]2 def delvalue (t):3     GlobalLi #没懂为什么一定要加这个4I=05      whilei<Len (LI):6         ifli[i]==T:7left=Li[:i]8 print (left)9right=li[i+1:]Ten # Print (i) Oneli=left+ Right Ai + =1 -  -Delvalue (6)

Delete all the values

Python Note 006--function