Define a procedure that finds the index of the second instance of a string in a a larger string-CodePudding

I am new to python, may i know

Define a procedure that finds the index of the second instance of a string in a larger string.

def find_second(findin, whattofind):
      return 

find_second('dance, dance, dance everyday', 'dance')
find_second('learning about data, surprisingly, requires a lot of data','data')

CodePudding user response：

You can use the find() method of strings to know the position of a string inside another string. Since it allows you to specify where to start searching, you can ignore the first occurrence.

Check the following example:

def find_second(haystack, needle):
    first = haystack.find(needle)

    second = haystack.find(needle, first   1) # We add 1 to skip the first occurrence

    return second

This function returns the starting index of the second occurrence of the string needle found in haystack.

CodePudding user response：

Second index can be found by searching after the first index

You can use index() or find() for strings.

def find_second(findin, whattofind):
    return findin.index(whattofind,findin.index(whattofind) 1)

find_second('dance, dance, dance everyday', 'dance')
find_second('learning about data, surprisingly, requires a lot of data','data')
#output
7
53

Or with find()

def find_second(findin, whattofind):
    return findin.find(whattofind,findin.find(whattofind) 1)

print(find_second('dance, dance, dance everyday', 'dance'))
print(find_second('learning about data, surprisingly, requires a lot of data','data'))
#output
7
53