Python string replace the values

[Irv Kalb]

> On Sep 1, 2017, at 10:13 AM, Ganesh Pal <ganesh1pal at gmail.com> wrote:
> 
> In the fixed length string i.e "a0000",last 4 bits i.e "0000" should be
> replaced by the user provided value ( the value is between 0001 + f f f f )
> . I intend to form  final_string  using a fixed_string and an user provided
> user_string
> 
> 
> Example:
> 
> fixed_string = "a0000"
> user_string ='1'
> 
> final string = fixed_string  and  user_string
> 
> Example :
> 
>  "a0000" and "1" => a0001
> 
>  "a0000" and "aa" => c00aa
> 
> 
> PS :  "and" this is not logical and it's just for example
> 
> If I concatenation using + or +=  or it's append the value at the end of
> the string
> 
>>>> "a0000" + "1"    ===> expected was a0001
> 'a00001'
> 
> 
> 
> I am on python 2.7 and Linux ,  any ideas that you recommend  to handle
> this
> 
> 
> Regards,
> Ganesh
> 

Here's a little function that should it it for you.  

(I assume that in your example "a0000" and "aa" => c00aa,  that really should have been   a00aa)

This should work for any size fixed_string and user_string (as long as the user_string is not longer than the fixed_string)

def mergeStrings(fixed_string, user_string):
    nCharsInFixedString = len(fixed_string)
    nCharsInUserString = len(user_string)

    nCharsToGetFromFixedString = nCharsInFixedString - nCharsInUserString

    finalString = fixed_string[:nCharsToGetFromFixedString] + user_string

    return finalString

Irv