ranges.c

来自「这是用matlab编写的支持向量机的函数工具箱」· C语言 代码 · 共 102 行

#include <stdio.h>
#include <stdlib.h>
#include "ranges.h"

void parse_range(char *str, int *low, int *high, int *modulus)
/* Parses a string of the following form: [@][low][:[high]][+modulus], where
   'low' and 'high' must be a non-negative integers; 'modulus' must be a
   positive integer.  If 'low' is omitted, it defaults to one (not zero, even
   though zero is a legal value).  If 'modulus' is omitted, it defaults to
   zero.  If 'high' is omitted but the colon or a modulus is present, 'high'
   is set to -1 as a signal to the caller.  If just a single number appears,
   it is interpreted as a value for 'low', and 'high' is set to -2. If an
   initial @ appears, '-low' is returned instead of 'low'. Something must
   appear (i.e. the empty string is not legal).

   The caller provides pointers to places to store 'low', 'high', and
   'modulus'.  The pointer for 'modulus' may be null, in which case a modulus
   specification is illegal.

   Incorrect specifications lead to an error message being displayed, and the
   program being terminated.  The checks include verifying that low<=high
   when 'high' is specified, but the caller may need to check this also after
   in cases where 'high' is left to default. */
{
  char *s;

  s = str;
  if (*s==0) goto error;
  if (*s=='@') s += 1;                                /* skip an initial '@' */

  *low = 1;                   /* look for value for 'low', or let it default */
  if (*s>='0' && *s<='9') {
    *low = 0;
    while (*s>='0' && *s<='9') { *low = 10*(*low) + (*s-'0'); s += 1; }
  }
  if (*str=='@') *low = -*low;                 /* negate low iff leading '@' */

  *high = *s==0 ? -2 : -1;                     /* look for value for 'high', */
  if (*s==':') {                                    /* or signal its absence */
    s += 1;
    if (*s!=0 && *s>='0' && *s<='9') {
      *high = 0;
      while (*s>='0' && *s<='9') { *high = 10*(*high) + (*s-'0'); s += 1; }
      if (*high<*low){
        fprintf(stderr,"High end of range is less than low end: %s\n",str);
        exit(1); }
    }
  }

  if (modulus!=0) *modulus = 0;              /* look for value for 'modulus' */
  if (*s=='+') {                         /* if it's legal, or let it default */
    if (modulus==0) goto error;
    s += 1;
    *modulus = 0;
    while (*s>='0' && *s<='9') { *modulus = 10*(*modulus) + (*s-'0'); s += 1; }
    if (*modulus==0) goto error;
  }

  if (*s!=0) goto error;                         /* check for garbage at end */
  return;

error:                                                       /* report error */
  fprintf(stderr,"Bad range specification: %s\n",str); exit(1);
}

void parse_length(char *str, int *length, int *modulus)
/* Parses a string of the following form: [@]length[{%|+}modulus], where
   'length' must be a non-negative integer; 'modulus' must be a positive
   integer. If the optional initial @ was found, then -length is returned
   to signal this. 'modulus' defaults to 1. If a + was given instead of a %,
   then -modulus is retuned; The caller provides pointers to places to
   store 'length' and 'modulus'. Incorrect specifications lead to an error
   message being displayed, and the program being terminated.  */
{
  char *s;
  int neg = 0;

  s = str;  
  if (*s==0) goto error;
  if (*s=='@') s += 1;                                /* skip an initial '@' */
  *length = 0;
  while (*s>='0' && *s<='9') { *length = 10*(*length) + (*s-'0'); s++; }
  if (*length==0) goto error;
  if (*str=='@') *length = -*length;               /* negate iff leading '@' */

  *modulus = 1;           /* look for value for 'modulus', or let it default */
  if (*s=='%' || *s=='+') {
    if (*s=='+') neg = 1;
    s += 1;
    *modulus = 0;
    while (*s>='0' && *s<='9') { *modulus = 10*(*modulus) + (*s-'0'); s++; }
    if (*modulus==0) goto error;
    if (neg) *modulus = -*modulus;
  }

  if (*s!=0) goto error;                         /* check for garbage at end */
  return;

error:                                                       /* report error */
  fprintf(stderr,"Bad length specification: %s\n",str); exit(1);
}