Python Is there an equivalent of mid right and left from BASIC

Question

I want to do something like this        gt  gt  gt  mystring    foo       gt  gt  gt  print mid mystring     Help

User · Answer

There are built-in functions in Python for  right  and  left   if you are looking for a boolean result   str    this is a test  left   str startswith  this   print left   gt  True  right   str endswith  test   print right   gt  True

User · Answer

Thanks Andy W  I found that the mid   did not quite work as I expected and I modified as follows   def mid s  offset  amount       return s offset-1 offset amount-1    I performed the following test   print   1 23   mid  123   1  1   print  1 2 3   mid  123   2  1   print  12 3    mid  123   3  1   print   12 3   mid  123   1  2   print  1 23    mid  123   2  2     Which resulted in    1 23 1 1 2 3 2 12 3  3  12 3 12 1 23  23   Which was what I was expecting   The original mid   code produces this    1 23 2 1 2 3 3 12 3    12 3 23 1 23  3   But the left   and right   functions work fine   Thank you

User · Answer

You can use this method also it will act like that  thadari  1 2 3 4 5 6    Front Two Left  print thadari  2    1 2    Last Two Right   edited print thadari -2     5 6    mid mid   len thadari    2  lefthalf   thadari  mid   1 2 3  righthalf   thadari mid    4 5 6    Hope it will help

User · Answer

slices to the rescue       def left s  amount       return s  amount   def right s  amount       return s -amount    def mid s  offset  amount       return s offset offset amount

User · Answer

These work great for reading left   right  n  characters from a string  but  at least with BBC BASIC  the LEFT    and RIGHT    functions allowed you to change the left   right  n  characters too     E g    10 a   00000  20 RIGHT  a  3   ABC  30 PRINT a    Would produce   00ABC   Edit   Since writing this  I ve come up with my own solution     def left s  amount   1  substring            if  substring                 return s  amount      else          if  len substring   gt  amount               substring   substring  amount          return substring   s  -amount   def right s  amount   1  substring            if  substring                 return s -amount       else          if  len substring   gt  amount               substring   substring  amount          return s  -amount    substring   To return n characters you d call   substring   left string  lt n gt     Where  defaults to 1 if not supplied  The same is true for right    To change the left or right n characters of a string you d call  newstring   left string  lt n gt  substring    This would take the first n characters of substring and overwrite the first n characters of string  returning the result in newstring  The same works for right

User · Answer

If I remember my QBasic  right  left and mid do something like this    gt  gt  gt  s    123456789   gt  gt  gt  s -2    89   gt  gt  gt  s  2   12   gt  gt  gt  s 4 6   56    http   www angelfire com scifi nightcode prglang qbasic function strings left right html

User · Answer

This is Andy s solution   I just addressed User2357112 s concern and gave it meaningful variable names   I m a Python rookie and preferred these functions   def left aString  howMany       if howMany  lt 1          return        else          return aString  howMany   def right aString  howMany       if howMany  lt 1          return        else          return aString -howMany    def mid aString  startChar  howMany       if howMany  lt  1          return        else          return aString startChar startChar howMany

[python] Python: Is there an equivalent of mid, right, and left from BASIC?

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