Convert hex string to int in Python

Question

How do I convert a hex string to an int in Python    I may have it as  0xffff  or just  ffff

User · Answer

The worst way    gt  gt  gt  def hex to int x       return eval  0x    x    gt  gt  gt  hex to int  c0ffee   12648430   Please don t do this   Is using eval in Python a bad practice

User · Answer

If you are using the python interpreter  you can just type 0x your hex value  and the interpreter will convert it automatically for you    gt  gt  gt  0xffff  65535

User · Answer

int hexstring  16  does the trick  and works with and without the 0x prefix   gt  gt  gt  int  quot a quot   16  10  gt  gt  gt  int  quot 0xa quot   16  10

User · Answer

For any given string s   int s  16

User · Answer

In Python 2 7  int  deadbeef  10  doesn t seem to work    The following works for me    gt  gt a   int  deadbeef  16   gt  gt float a  3735928559 0

User · Answer

Handles hex  octal  binary  int  and float  Using the standard prefixes  i e  0x  0b  0  and 0o   this function will convert any suitable string to a number   I answered this here  https   stackoverflow com a 58997070 2464381 but here is the needed function   def to number n           Convert any number representation to a number      This covers  float  decimal  hex  and octal numbers               try          return int str n   0      except          try                python 3 doesn t accept  010  as a valid octal   You must use the                0o  prefix             return int  0o    n  0          except              return float n

User · Answer

Handles hex  octal  binary  int  and float  Using the standard prefixes  i e  0x  0b  0  and 0o   this function will convert any suitable string to a number   I answered this here  https   stackoverflow com a 58997070 2464381 but here is the needed function   def to number n           Convert any number representation to a number      This covers  float  decimal  hex  and octal numbers               try          return int str n   0      except          try                python 3 doesn t accept  010  as a valid octal   You must use the                0o  prefix             return int  0o    n  0          except              return float n

User · Answer

Or ast literal eval  this is safe  unlike eval    ast literal eval  0xffff     Demo    gt  gt  gt  import ast  gt  gt  gt  ast literal eval  0xffff   65535  gt  gt  gt

User · Answer

The worst way    gt  gt  gt  def hex to int x       return eval  0x    x    gt  gt  gt  hex to int  c0ffee   12648430   Please don t do this   Is using eval in Python a bad practice

User · Answer

Without the 0x prefix  you need to specify the base explicitly  otherwise there s no way to tell  x   int  quot deadbeef quot   16   With the 0x prefix  Python can distinguish hex and decimal automatically   gt  gt  gt  print int  quot 0xdeadbeef quot   0   3735928559  gt  gt  gt  print int  quot 10 quot   0   10   You must specify 0 as the base in order to invoke this prefix-guessing behavior  if you omit the second parameter int   will assume base-10

User · Answer

Without the 0x prefix  you need to specify the base explicitly  otherwise there s no way to tell  x   int  quot deadbeef quot   16   With the 0x prefix  Python can distinguish hex and decimal automatically   gt  gt  gt  print int  quot 0xdeadbeef quot   0   3735928559  gt  gt  gt  print int  quot 10 quot   0   10   You must specify 0 as the base in order to invoke this prefix-guessing behavior  if you omit the second parameter int   will assume base-10

User · Answer

If you are using the python interpreter  you can just type 0x your hex value  and the interpreter will convert it automatically for you    gt  gt  gt  0xffff  65535

User · Answer

Without the 0x prefix  you need to specify the base explicitly  otherwise there s no way to tell  x   int  quot deadbeef quot   16   With the 0x prefix  Python can distinguish hex and decimal automatically   gt  gt  gt  print int  quot 0xdeadbeef quot   0   3735928559  gt  gt  gt  print int  quot 10 quot   0   10   You must specify 0 as the base in order to invoke this prefix-guessing behavior  if you omit the second parameter int   will assume base-10

User · Answer

Without the 0x prefix  you need to specify the base explicitly  otherwise there s no way to tell  x   int  quot deadbeef quot   16   With the 0x prefix  Python can distinguish hex and decimal automatically   gt  gt  gt  print int  quot 0xdeadbeef quot   0   3735928559  gt  gt  gt  print int  quot 10 quot   0   10   You must specify 0 as the base in order to invoke this prefix-guessing behavior  if you omit the second parameter int   will assume base-10

User · Answer

For any given string s   int s  16

User · Answer

The formatter option   x    seems to work in assignment statements as well for me   Assuming Python 3 0 and later   Example   a   int  0x100   16  print a     256 print   x    a   100 b   a print b   256 c     x    a print c   100

User · Answer

In Python 2 7  int  deadbeef  10  doesn t seem to work    The following works for me    gt  gt a   int  deadbeef  16   gt  gt float a  3735928559 0

User · Answer

with  0x  prefix  you might also use eval function  For example   gt  gt a  0xff   gt  gt eval a  255

User · Answer

For any given string s   int s  16

User · Answer

int hexstring  16  does the trick  and works with and without the 0x prefix   gt  gt  gt  int  quot a quot   16  10  gt  gt  gt  int  quot 0xa quot   16  10

User · Answer

The formatter option   x    seems to work in assignment statements as well for me   Assuming Python 3 0 and later   Example   a   int  0x100   16  print a     256 print   x    a   100 b   a print b   256 c     x    a print c   100

User · Answer

Adding to Dan s answer above  if you supply the int   function with a hex string  you will have to specify the base as 16 or it will not think you gave it a valid value  Specifying base 16 is unnecessary for hex numbers not contained in strings   print int 0xdeadbeef    valid  myHex    0xdeadbeef  print int myHex    invalid  raises ValueError print int myHex   16    valid

User · Answer

with  0x  prefix  you might also use eval function  For example   gt  gt a  0xff   gt  gt eval a  255

User · Answer

Convert hex string to int in Python I may have it as  quot 0xffff quot  or just  quot ffff quot    To convert a string to an int  pass the string to int along with the base you are converting from  Both strings will suffice for conversion in this way   gt  gt  gt  string 1    quot 0xffff quot   gt  gt  gt  string 2    quot ffff quot   gt  gt  gt  int string 1  16  65535  gt  gt  gt  int string 2  16  65535  Letting int infer If you pass 0 as the base  int will infer the base from the prefix in the string   gt  gt  gt  int string 1  0  65535  Without the hexadecimal prefix  0x  int does not have enough information with which to guess   gt  gt  gt  int string 2  0  Traceback  most recent call last     File  quot  lt stdin gt  quot   line 1  in  lt module gt  ValueError  invalid literal for int   with base 0   ffff   literals  If you re typing into source code or an interpreter  Python will make the conversion for you   gt  gt  gt  integer   0xffff  gt  gt  gt  integer 65535  This won t work with ffff because Python will think you re trying to write a legitimate Python name instead   gt  gt  gt  integer   ffff Traceback  most recent call last     File  quot  lt stdin gt  quot   line 1  in  lt module gt  NameError  name  ffff  is not defined  Python numbers start with a numeric character  while Python names cannot start with a numeric character

User · Answer

int hexstring  16  does the trick  and works with and without the 0x prefix   gt  gt  gt  int  quot a quot   16  10  gt  gt  gt  int  quot 0xa quot   16  10

User · Answer

Convert hex string to int in Python I may have it as  quot 0xffff quot  or just  quot ffff quot    To convert a string to an int  pass the string to int along with the base you are converting from  Both strings will suffice for conversion in this way   gt  gt  gt  string 1    quot 0xffff quot   gt  gt  gt  string 2    quot ffff quot   gt  gt  gt  int string 1  16  65535  gt  gt  gt  int string 2  16  65535  Letting int infer If you pass 0 as the base  int will infer the base from the prefix in the string   gt  gt  gt  int string 1  0  65535  Without the hexadecimal prefix  0x  int does not have enough information with which to guess   gt  gt  gt  int string 2  0  Traceback  most recent call last     File  quot  lt stdin gt  quot   line 1  in  lt module gt  ValueError  invalid literal for int   with base 0   ffff   literals  If you re typing into source code or an interpreter  Python will make the conversion for you   gt  gt  gt  integer   0xffff  gt  gt  gt  integer 65535  This won t work with ffff because Python will think you re trying to write a legitimate Python name instead   gt  gt  gt  integer   ffff Traceback  most recent call last     File  quot  lt stdin gt  quot   line 1  in  lt module gt  NameError  name  ffff  is not defined  Python numbers start with a numeric character  while Python names cannot start with a numeric character

User · Answer

For any given string s   int s  16

User · Answer

int hexstring  16  does the trick  and works with and without the 0x prefix   gt  gt  gt  int  quot a quot   16  10  gt  gt  gt  int  quot 0xa quot   16  10

User · Answer

Adding to Dan s answer above  if you supply the int   function with a hex string  you will have to specify the base as 16 or it will not think you gave it a valid value  Specifying base 16 is unnecessary for hex numbers not contained in strings   print int 0xdeadbeef    valid  myHex    0xdeadbeef  print int myHex    invalid  raises ValueError print int myHex   16    valid

User · Answer

Or ast literal eval  this is safe  unlike eval    ast literal eval  0xffff     Demo    gt  gt  gt  import ast  gt  gt  gt  ast literal eval  0xffff   65535  gt  gt  gt

[python] Convert hex string to int in Python

Please don't do this!

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