line_number.c

[詳解]

/*++
/* NAME
/*  line_number 3
/* SUMMARY
/*  line number utilities
/* SYNOPSIS
/*  #include <line_number.h>
/*
/*  char    *format_line_number(result, first, last)
/*  VSTRING *buffer;
/*  ssize_t first;
/*  ssize_t lastl
/* DESCRIPTION
/*  format_line_number() formats a line number or number range.
/*  The output is <first-number>-<last-number> when the numbers
/*  differ, <first-number> when the numbers are identical.
/* .IP result
/*  Result buffer, or null-pointer. In the latter case the
/*  result is stored in a static buffer that is overwritten
/*  with subsequent calls. The function result value is a
/*  pointer into the result buffer.
/* .IP first
/*  First line number.
/* .IP last
/*  Last line number.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

 /*
  * System library.
  */
#include <sys_defs.h>

 /*
  * Utility library.
  */
#include <vstring.h>
#include <line_number.h>

/* format_line_number - pretty-print line number or number range */

char   *format_line_number(VSTRING *result, ssize_t first, ssize_t last)
{
    static VSTRING *buf;

    /*
     * Your buffer or mine?
     */
    if (result == 0) {
    if (buf == 0)
        buf = vstring_alloc(10);
    result = buf;
    }

    /*
     * Print a range only when the numbers differ.
     */
    vstring_sprintf(result, "%ld", (long) first);
    if (first != last)
    vstring_sprintf_append(result, "-%ld", (long) last);

    return (vstring_str(result));
}