cc [ flag... ] file... -lcpc [ library... ]
#include <libcpc.h>

typedef void (cpc_errfn_t)(const char *fn, const char *fmt, va_list ap);

void cpc_seterrfn(cpc_errfn_t *errfn);

For the convenience of programmers instrumenting their code, several libcpc(3LIB) functions automatically emit to stderr error messages that attempt to provide a more detailed explanation of their error return values. While this can be useful for simple programs, some applications may wish to report their errors differently\(emfor example, to a window or to a log file.

The cpc_seterrfn() function allows the caller to provide an alternate function for reporting errors; the type signature is shown above. The fn argument is passed the library function name that detected the error, the format string fmt and argument pointer ap can be passed directly to vsnprintf(3C) or similar varargs-based routine for formatting.

The default printing routine can be restored by calling the routine with an errfn argument of NULL.

Example 1 Debugging example.

This example produces error messages only when debugging the program containing it, or when the cpc_strtoevent() function is reporting an error when parsing an event specification

int debugging;
void
myapp_errfn(const char *fn, const char *fmt, va_list ap)
{
 if (strcmp(fn, "strtoevent") != 0 && !debugging)
 return;
 (void) fprintf(stderr, "myapp: cpc_%s(): ", fn);
 (void) vfprintf(stderr, fmt, ap);
}

See attributes(7) for descriptions of the following attributes:

vsnprintf (3C), cpc (3CPC), cpc_seterrhndlr (3CPC), libcpc (3LIB), attributes (7)

The cpc_seterrfn() function exists for binary compatibility only. Source containing this function will not compile. This function is obsolete and might be removed in a future release. Applications should use cpc_seterrhndlr(3CPC) instead.