nRF52840 Zephyr sscanf() issue

[newUser]

To parse information from strings I want to use sscanf().

Currently I have this small test program:

#include <stdio.h>
#include <stdint.h>

int main()
{
  char *pUrc = "+QIOPEN: 0,0";
  uint8_t  socket;
  uint32_t result;
  printf("sscanf(): %d -> socket: %u, result: %u\n", sscanf(pUrc, "+QIOPEN: %hhu,%u", &socket, &result), socket, result);

  return 0;
}

And in the prj.conf I have CONFIG_NEWLIB_LIBC=y defined.

This program produces two different outputs:
Zephyr:

sscanf(): 1 -> socket: 0, result: 3758157056

onlinegdb:

sscanf(): 2 -> socket: 0, result: 0

What is going on here? I would expect the second output, the one onlinegdb is producing.

[newUser]

I have replaced %hhu with %u, and made socket a uint32_t. This solved it.

Does the sscanf() implementation on this platform not support smaller types?

[Didrik Rokhaug]

Hi,

It's good to hear that you found a solution.

You can also set CONFIG_NEWLIB_LIBC_NANO=n to get the full version of Newlib, and not just the "nano" version. That will also make your test program work as expected.

Best regards,

Didrik