atoi64.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

/*
 * COPYRIGHT:   See COPYING in the top level directory
 * PROJECT:     ReactOS system libraries
 * FILE:        lib/crt/??????
 * PURPOSE:     Unknown
 * PROGRAMER:   Unknown
 * UPDATE HISTORY:
 *              25/11/05: Added license header
 */

#include <precomp.h>

/*
 * @implemented
 */
__int64
_atoi64(const char *nptr)
{
  char *s = (char *)nptr;
  __int64 acc = 0;
  int neg = 0;

  while(isspace((int)*s))
    s++;
  if (*s == '-')
    {
      neg = 1;
      s++;
    }
  else if (*s == '+')
    s++;

  while (isdigit((int)*s))
    {
      acc = 10 * acc + ((int)*s - '0');
      s++;
    }

  if (neg)
    acc *= -1;
  return acc;
}