itoa() 函数的转换原理是什么啊

只看该作者 · 2013-10-22 22:39

static char *itoa(int value, char *string, int radix)
{
int    i, d;
int    flag = 0;
char *ptr = string;
   /* This implementation only works for decimal numbers. */
    if (radix != 10)
    {
   *ptr = 0;
   return string;
    }

    if (!value)
    {
   *ptr++ = 0x30;
   *ptr = 0;
   return string;
    }

    /* if this is a negative value insert the minus sign. */
    if (value < 0)
    {
   *ptr++ = '-';
   /* Make the value positive. */
   value *= -1;
    }
    for (i = 10000; i > 0; i /= 10)
    {
   d = value / i;
   if (d || flag)
   {
      *ptr++ = (char)(d + 0x30);
      value -= (d * i);
      flag = 1;
   }
    }

  /* Null terminate the string. */
  *ptr = 0;
  return string;
}/* NCL_Itoa */
求换算原理

只看该作者 · 2013-10-25 10:43

不就是字符'2'=0x32  数字 2 =0x2;

如 value = 222 ==>"222";

其他代码自己看看就明白了
for (i = 10000; i > 0; i /= 10)  ==> int 表示的最大位数 9

/* if this is a negative value insert the minus sign. */
      if (value < 0) ==> 负数 -