另外，給妳個修改過的源碼，相當於_atoi64，返回的數為long long 類型，可以支持比4294967295 大的數字的處理。
long long MY_atol( const char *nptr )
{
int c; /* current char */
long long total; /* current total */
int sign; /* if '-', then negative, otherwise positive */
/* skip whitespace */
while ( isspace((int)(unsigned char)*nptr) )
++nptr;
c = (int)(unsigned char)*nptr++;
sign = c; /* save sign indication */
if (c == '-' || c == '+')
c = (int)(unsigned char)*nptr++; /* skip sign */
total = 0;
while (isdigit(c)) {
total = 10 * total + (c - '0'); /* accumulate digit */
c = (int)(unsigned char)*nptr++; /* get next char */
}
if (sign == '-')
return -total;
else
return total; /* return result, negated if necessary */
}