Convert string to integer

[misterlisty]

Using BLE to set a integer variable in my code but i can only write a hex or string value. Hoe do i convert a string or Hex value to an integer?

Unhandled exception in callback handler
Traceback (most recent call last):
 File "main.py", line 445, in _mqtt_handler
 File "boot.py", line 31, in logger
TypeError: unsupported types for __ge__: 'bytes', 'int'

[robert-hh]

@misterlisty If it is a string, you can use int:

val = int("1234") -> 1234
val = int("ab13", 16) -> 43975

If it is a hex string, you can use binascii.hexlify(), like

binascii.hexlify("\x12") -> '12'

If you want to convert a bytearray with bytes to an integer, you can use int.from_bytes()

val = int.from_bytes("\x12\x34", "little") --> 4660

The opposite exists too.

P.S.: These are standard Python functions. The only problem here might be, that MicoPython may not cover all variants.

[jclo13]

hello @robert-hh

I have this error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported types for __add__: 'NoneType', 'int'

I want to use a counter whit the deepsleep, and I am using

i = pycom.nvs_get('i')
pycom.nvs_set('i', i+1)

Is there a way to make to counter?

Thank You in advance.

Jose

[robert-hh]

@jclo13
I assume that the first time you called nvs_get the key 'i' did not exist, and the call returned None, which caused the error at the second line. So you will need something like:

import pycom
i = pycom.nvs_get('i')
if i is not None:
    pycom.nvs_set('i', i+1)
else:
    pycom.nvs_set('i', 0)

You could as well write it with a ternary expression:

import pycom
i = pycom.nvs_get('i')
pycom.nvs_set('i', 0 if i is None else i+1)

[jclo13]

@robert-hh, it worked, thank you.

[warrenfelsh]

Without the 0x prefix, you need to specify the base explicitly, otherwise there's no way to tell:

x = int("deadbeef", 16)

With the 0x prefix, Python can distinguish hex and decimal automatically.

print int("0xdeadbeef", 0)
3735928559

[kjm]

@robert-hh said in Convert string to integer:

binascii.hexlify("\x12")

On my gpy binascii.hexlify("\x12") gives b'12' Rob. How come I get bytes but you get a hex string?