printf %llu with error

[PeterMu]

Hi guys,

I'm executing the "printf" in CubeIDE to output uint64_t with "%llu", but the printout is wrong.

Why does it not support "%llu"?

However it can work well in Keil.

//debug.c
int __io_putchar(int ch) //Redirect printf to uart
{
  HAL_UART_Transmit(&huart1, (uint8_t *)&ch, 1, 0xFFFF);
  return (ch);
}


//main.c
int main()
{
//***
printf("%llu\r\n", (uint64_t)1 );  //Hope to output "1", but output "lu"
}

[Pavel A.]

This is because the C runtime library in the GNU toolchain supplied with CubeIDE has limited implementation of printf. It does not support %ll and some other formats. Keil MDK provides their own runtime library, high quality and thread aware. This is one of reasons why Keil MDK is worth its price ))

[AScha.3]

Hi,

just a simple test : what its doing with :  "%lu" ?

printf("%lu\r\n", (uint64_t)1 ); 

[PeterMu]

I used a ftp server lib which actually used "%llu"，this makes my project cannot work. because it returns wrong message from ftp server.

[PeterMu · Accepted solution]

Hi,

Thanks for answering, I found that CubeIDE uses the "reduced C", and the problem can be solved by modifying to "standard C" .