SAS/C Library Reference, Vol. 1

vsprintf -- Write Formatted Output to a String

SYNOPSIS

 #include <stdarg.h>
 #include <stdio.h>

 int vsprintf(char *s, const char *format, va_list arg);

DESCRIPTION

vsprintf is equivalent to sprintf with arg replacing the variable-argument list. arg has been initialized by the va_start macro and possibly va_arg calls. vsprintf does not invoke the va_end macro. See va_arg, va_end, and va_start for details on varying-length argument-list functions.

RETURN VALUE

vsprintf returns the number of characters written in the array, not counting the terminating-null character.

EXAMPLE

  #include <stdio.h>
  #include <stdarg.h>
  #include <string.h>

  static void format_msg(char *, int, int, ...);

  #define NOTE 0
  #define WARNING 1

  main()
  {
     char msgbuf[100];
     format_msg(msgbuf, NOTE, 0);
     printf("The formatted message is: "%s" n", msgbuf);
     format_msg(msgbuf, WARNING,1, "a replacement string");
     printf("The formatted message is: "%s" n", msgbuf);
     return;
  }

  static const char *msgs[]  = {
     "This is message number zero",
     "This message requires %s"
  };

  static const char *levels[]  = {
     "NOTE: ",
     "WARNING: "
  };

  static void format_msg(char *buf, int msgno, int level, ...)
  {
     va_list args;
     va_start(args, level);

        /* Copy in the message prefix. Format the     */
        /*  remainder of the message with vsprintf(). */
     strcpy(buf, levels[level]);
     vsprintf(buf + strlen(levels[level]),msgs[msgno], args);
     va_end(args);
  }

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