file that can compress any string using zlib compression library

my_gzip.c

#include "zlib.h"
#include <stdio.h>

#if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__)
#  include <fcntl.h>
#  include <io.h>
#  ifdef UNDER_CE
#    include <stdlib.h>
#  endif
#  define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
#else
#  define SET_BINARY_MODE(file)
#endif

static char *prog;

static void error(const char *msg);
static void gz_compress(const char *in, gzFile out);
int  main(int argc, char *argv[]);

static void error(msg)
    const char *msg;
{
    fprintf(stderr, "%s: %s\n", prog, msg);
    exit(1);
}

static void gz_compress(in, out)
    const char *in;
    gzFile out;
{
    int len = strlen(in);
    int err;
    if(gzwrite(out, in, (unsigned) len) != len) error(gzerror(out, &err));
}

int main(argc, argv)
    int argc;
    char *argv[];
{
    gzFile outfile;
    char outmode[] = "wb1";

    prog = argv[0];

    outfile = gzdopen(fileno(stdout), outmode);
    SET_BINARY_MODE(stdout);
    gz_compress("Hello ", outfile);
    gz_compress("World!", outfile);
    if(gzclose(outfile) != Z_OK) error("failed gzclose");
}