files.c

This example demonstrates when and how the ewarn() function is used.

err() is called when a fatal error occurs. ewarn() is called when a nonfatal error occurs.

Compare this example with hello.c, which demonstrates warn(). In hello.c, warn() is called after an unusual but managable situation with the program arguments is found. In this example, ewarn() is called after a necessary library function fails. We will get a more detailed error message with ewarn() because it looks at errno when writing its message.

/**
 * @example files.c
 * This example demonstrates when and how the ewarn() function is used.
 *
 * err() is called when a fatal error occurs. ewarn() is called when a nonfatal
 * error occurs.
 *
 * Compare this example with hello.c, which demonstrates warn(). In hello.c,
 * warn() is called after an unusual but managable situation with the program
 * arguments is found. In this example, ewarn() is called after a necessary
 * library function fails. We will get a more detailed error message with
 * ewarn() because it looks at errno when writing its message.
 */
 
#include <stdio.h>
#include <stdlib.h>
 
#include "../err.h"
 
int
main(int argc, char *argv[])
{
        int i;
 
        program_invocation_name = argv[0];
 
        if (argc < 2)
                err("no files provided");
 
        for (i = 1; i < argc; i++) {
                FILE *fp;
                int c;
 
                if ((fp = fopen(argv[i], "r")) == NULL) {
                        ewarn("%s", argv[i]);
                        continue;
                }
 
                while ((c = fgetc(fp)) != EOF)
                        putchar(c);
 
                fclose(fp);
        }
 
        return EXIT_SUCCESS;
}