How to check if a variable is an integer or a string

Question

I have an application that has a couple of commands  When you type a certain command  you have to type in additional info about something someone  Now that info has to be strictly an integer or a string  depending on the situation   However  whatever you type into Python using raw input   actually is a string  no matter what  so more specifically  how would I shortly and without try   except see if a variable is made of digits or characters

User · Answer

Depending on your definition of shortly  you could use one of the following options    try  int your input   except ValueError        your input isdigit   use a regex use parse which is kind of the opposite of format

User · Answer

Don t check  Go ahead and assume that it is the right input  and catch an exception if it isn t   intresult   None while intresult is None      input   raw input       try  intresult   int input      except ValueError  pass

User · Answer

The isdigit method of the str type returns True iff the given string is nothing but one or more digits   If it s not  you know the string should be treated as just a string

User · Answer

if you want to check what it is    gt  gt  gt isinstance 1 str  False  gt  gt  gt isinstance  stuff  str  True  gt  gt  gt isinstance 1 int  True  gt  gt  gt isinstance  stuff  int  False   if you want to get ints from raw input   gt  gt  gt x raw input  enter thing    enter thing  3  gt  gt  gt try  x   int x     except  pass   gt  gt  gt isinstance x int  True

User · Answer

In my opinion you have two options    Just try to convert it to an int  but catch the exception   try      value   int value  except ValueError      pass    it was a string  not an int    This is the Ask Forgiveness approach  Explicitly test if there are only digits in the string   value isdigit     str isdigit   returns True only if all characters in the string are digits  0-9    The unicode   Python 3 str type equivalent is unicode isdecimal     str isdecimal    only Unicode decimals can be converted to integers  as not all digits have an actual integer value  U 00B2 SUPERSCRIPT 2 is a digit  but not a decimal  for example    This is often called the Ask Permission approach  or Look Before You Leap     The latter will not detect all valid int   values  as whitespace and   and - are also allowed in int   values  The first form will happily accept     10    as a number  the latter won t   If your expect that the user normally will input an integer  use the first form  It is easier  and faster  to ask for forgiveness rather than for permission in that case

[python] How to check if a variable is an integer or a string?

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