books/apitue/sample-code/11/crypt.c

45 lines
1.1 KiB
C

/* This file is part of the sample code and exercises
* used by the class "Advanced Programming in the UNIX
* Environment" taught by Jan Schaumann
* <jschauma@netmeister.org> at Stevens Institute of
* Technology.
*
* This file is in the public domain.
*
* You don't have to, but if you feel like
* acknowledging where you got this code, you may
* reference me by name, email address, or point
* people to the course website:
* https://stevens.netmeister.org/631/
*/
/* A simple program to introduce the concept of shared libraries.
*
* Compiling this program will work, as we have the forward declaration
* from the header. Linking the executable will fail,
* unless we explicitly link against libcrypt.
*
* Compare
* cc -Wall -Werror -Wextra crypt.c -lcrypt
* cc -Wall -Werror -Wextra -rdynamic dlopenex.c -dl
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
void
printCrypt(const char *s) {
(void)printf("%s\n", crypt(s, "$1"));
}
int
main(int argc, char **argv) {
if (argc != 2) {
(void)fprintf(stderr, "Usage: %s string\n", argv[0]);
exit(EXIT_FAILURE);
}
printCrypt(argv[1]);
exit(EXIT_SUCCESS);
}