Synopsis

(Required) Obsolescent language features shall not be used.

Enabled by default

Yes

Severity/Certainty

Medium/Medium

Full description

The use of ungetc on a binary stream where the file position indicator is zero prior to the call is an obsolescent feature.

Coding standards

Code examples

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

#include <stdio.h>

void fail(void) 
{
   FILE *fp;
   ungetc ('+', fp);
}

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

#include <stdio.h>

void pass(void) 
{
   FILE *fp;
   fp = fopen("file.txt", "r");
   getc(fp);
   ungetc ('+', fp);
}