Python judges that the string contains substrings (number, index, all positions)

Find the substring from left to right, if it exists, output the index value of the first character of the substring, if it does not exist, output -1

# find()a = 'love you'b = 'you'c = 'no'print(a.find(b)) #5print(a.find(c)) #-1

Find the substring from left to right, if it exists, output the index value of the first character of the substring, if it does not exist, output -1

# rfind()a = 'love you'b = 'you'c = 'no'print(a.rfind(b)) #5print(a.rfind(c)) #-1

Count the number of substrings in the parent string

# count()a = 'love you do you love me'b = 'you'c = 'no'print(a.count(b)) #2print(a.count(c)) #0

Find all the positions where the specified string contains substrings and return it as a list

def indexstr(str1,str2):'''Find all positions where the specified string str1 contains the specified substring str2, and return ''' in the form of a listlenth2=len(str2)lenth1=len(str1)indexstr2=[]i=0while str2 in str1[i:]:indextmp = str1.index(str2, i, lenth1)indexstr2.append(indextmp)i = (indextmp + length2)return indexstr2