Synopsis

(Required) The macro EOF shall only be compared with the unmodified return value from any Standard Library function capable of returning EOF

Enabled by default

Yes

Severity/Certainty

Medium/Medium

Full description

The macro EOF is compared with a value not originating from a function capable of returning EOF.

Coding standards

Code examples

The following code example fails the check and will give a warning:

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

void f1(void)
{
  char ch;
  ch = (char)getchar();
  /*
   * The following test is non-compliant. It will not be reliable as the
   * return value is cast to a narrower type before checking for EOF. */
  if (EOF != (int32_t) ch) {
  }
}

The following code example passes the check and will not give a warning about this issue:

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

void f2(void)
{
  char ch;
  ch = (char)getchar();
  if (!feof(stdin))
  {
  }
}

void f3(void)
{
  int32_t i_ch;
  i_ch = getchar();
  /*
   * The following test is compliant. It will be reliable as the
   * unconverted return value is used when checking for EOF. */
  if (EOF != i_ch)
  {
    char ch;
    ch = (char)i_ch;
  }
}