CODEWITHSUNDEEP
pythoncchartype-conversionunsigned
Panchove
Panchove

Reputation: 571

How to convert unsigned char to int with python

I have the following code in C

#include <stdio.h>

int main ()
{

  unsigned char mask = 0xAB;

  for (int i = 0; i < 20; i++)
    {
      printf ("%d - %x\n", mask, mask);
      mask += 9;
    }

  return 0;
}

Output in C

171 - ab
180 - b4
189 - bd
198 - c6
207 - cf
216 - d8
225 - e1
234 - ea
243 - f3
252 - fc
5 - 5
14 - e
23 - 17
32 - 20
41 - 29
50 - 32
59 - 3b
68 - 44
77 - 4d
86 - 56

Now in Python:

mask = 0xab
for i in range(20):
  print("{0:d} - {0:x}".format(mask,mask))
  mask = (mask + 9) % 0xFF

OutPut Python:

171 - ab
180 - b4
189 - bd
198 - c6
207 - cf
216 - d8
225 - e1
234 - ea
243 - f3
252 - fc
6 - 6
15 - f
24 - 18
33 - 21
42 - 2a
51 - 33
60 - 3c
69 - 45
78 - 4e
87 - 57

As you can see, the correct output is that of the C code, but in python I have tried in various ways using pack(), to_bytes() but I can't find the correct result, how can I correct it?

Thanks in advance

Upvotes: 1

Views: 685

Answers (1)

user459872
user459872

Reputation: 24907

You should modulo with 256(Hex: 0x100). This is because C unsigned char data type ranges from 0 to 255.

>>> mask = 0xab
>>> for i in range(20):
...   print("{0:d} - {0:x}".format(mask,mask))
...   mask = (mask + 9) % 0x100
...

This will produce the same output as like your C code!.

171 - ab
180 - b4
189 - bd
198 - c6
207 - cf
216 - d8
225 - e1
234 - ea
243 - f3
252 - fc
5 - 5
14 - e
23 - 17
32 - 20
41 - 29
50 - 32
59 - 3b
68 - 44
77 - 4d
86 - 56

Upvotes: 1

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