way to send strings to stdout AND socket in 1 line

Question

I want to write this to only 1 line:

fprintf(stdout, "RCPT TO: <%s>\r\n", argv[argc-1]);
fprintf(sockfd, "RCPT TO: <%s>\r\n", argv[argc-1]);

so i want to send the same string to stdout and to my open socket. How can I do this?

Answer 1

Not unless you want to write your own function that takes two File* and varargs, and calls fprintf twice.

Answer 2

With

#include <stdarg.h>

int fprintf_both(FILE *a, FILE *b, const char *fmt, ...)
{
  FILE *f[2];
  const int n = sizeof(f) / sizeof(f[0]);
  int i;
  int sum = 0;

  f[0] = a;
  f[1] = b;

  for (i = 0; i < n; i++) {
    va_list ap;
    int bytes;

    va_start(ap, fmt);
    bytes = vfprintf(f[i], fmt, ap);
    va_end(ap);

    if (bytes < 0)
      return bytes;
    else
      sum += bytes;
  }

  return sum;
}

you can

fprintf_both(stdout, sockfd, "RCPT TO: <%s>\r\n", argv[argc-1]);

Answer 3

I guess you want to do this to put it inside something like a while loop condition? You might like the C comma operator, e.g.

while ( f1(), f2() ) { //bla }

The comma causes f1() to be executed, it's return value discarded, followed by f2() and the its return value kept. (i.e. f2() should return an int or bool and f1() doesn't matter)