Format
#include <stdio.h>
int fileno(FILE *stream);Language Level: XPG4
Threadsafe: Yes.
Integrated File System Interface: This function is not available when SYSIFCOPT(*NOIFSIO) is specified on the compilation command.
Description
The fileno() function determines the file handle that is currently associated with stream.
Return Value
If the environment variable QIBM_USE_DESCRIPTOR_STDIO is set to Yes, the fileno()function returns 0 for stdin, 1 for stdout, and 2 for stderr.
With QIBM_USE_DESCRIPTOR_STDIO set to No, the ILE C session files stdin, stdout, and stderr do not have a file descriptor associated with them. The fileno() function will return a value of -1 in this case.
The value of errno can be set to EBADF.
Example that uses fileno()
This example determines the file handle of the stderr data stream.
/* Compile with SYSIFCOPT(*IFSIO) */
#include <stdio.h>
int main (void)
{
FILE *fp;
int result;
fp = fopen ("stderr","w");
result = fileno(fp);
printf("The file handle associated with stderr is %d.\n", result);
return 0;
/*****************************************************************
* The output should be:
*
* The file handle associated with stderr is -1.
****************************************************************/
}Related Information