Passing variables to system

[redruby147]

Id like to know how to pass variables to system, for example

 system(program %d, variable);

Im not sure how to do this.

Thanks

[matsp]

You'll want to use something like sprintf() to do that.

--
Mats

[rmetcalf]

Here's how I do it. I load a string with the entire command and pass it to the system call.

sprintf(sysstr,"program_name %d",variable);
system(sysstr);

[master5001]

Or even better yet...

Example:

#define BUFFERSIZE  4096 // 4k buffer should suffice.

int vsystem(const char *fmt, ...)
{
  va_list args;
  char buffer[BUFFERSIZE];

  args = va_start(args, fmt);
  /* A word of warning. This is kind of where it helps to look into a more buffer friendly version of
   * vsprintf() since there are issues when you do things like this. Microsoft has vsprintf_s() which
   * is more advisable to use than vsprintf() but you sacrifice portability then.
   */
  if(vsprintf(buffer, fmt, args) >= BUFFERSIZE)
    fprintf(stderr, "A buffer overflow probably already crashed the program. If not, just know that it did happen.");
  va_end(args);

  return system(buffer);
}

Now you can do nifty things like:

Example:

vsystem("gcc %s.c -c -o %s.o", user_input, user_input);

[redruby147]

nice, solved it, thanks ^^