C语言实现整形和字符串互转

1.整形转字符串

void Int2Str(u8* str, u32 intnum)
{
    u32 i, Div = 1000000000, j = 0, Status = 0;
   //32位无符号数最大是10位整数,所以Div=10 0000 0000
    for (i = 0; i < 10; i++)
    {
        str[j++] = (intnum / Div) + '0';//取最高位 转化成字符 

        intnum = intnum % Div;//去掉最高位
        Div /= 10;//还剩下10-i位要转换
        if ((str[j-1] == '0') & (Status == 0))//忽略最高位的'0'
        {
            j = 0;
        }
        else
        {
            Status++;
        }
    }
}

u8 str[]={0};

Int2Str(str,2018);
printf("%s",str);

2.字符串转整形

方法一（垃圾！！！）：

#define IS_CAP_LETTER(c)    (((c) >= 'A') && ((c) <= 'F'))
#define IS_LC_LETTER(c)     (((c) >= 'a') && ((c) <= 'f'))
#define IS_09(c)            (((c) >= '0') && ((c) <= '9'))
#define ISVALIDHEX(c)       (IS_CAP_LETTER(c) || IS_LC_LETTER(c) || IS_09(c))
#define ISVALIDDEC(c)       IS_09(c)
#define CONVERTDEC(c)       (c - '0')

#define CONVERTHEX_ALPHA(c) (IS_CAP_LETTER(c) ? ((c) - 'A'+10) : ((c) - 'a'+10))
#define CONVERTHEX(c)       (IS_09(c) ? ((c) - '0') : CONVERTHEX_ALPHA(c))

u32 Str2Int(u8 *p_inputstr, u32 *p_intnum)
{
  u32 i = 0, res = 0;
  u32 val = 0;

  if ((p_inputstr[0] == '0') && ((p_inputstr[1] == 'x') || (p_inputstr[1] == 'X')))
  {
    i = 2;
    while ( ( i < 11 ) && ( p_inputstr[i] != '\0' ) )
    {
      if (ISVALIDHEX(p_inputstr[i]))
      {
        val = (val << 4) + CONVERTHEX(p_inputstr[i]);
      }
      else
      {
        /* Return 0, Invalid input */
        res = 0;
        break;
      }
      i++;
    }

    /* valid result */
    if (p_inputstr[i] == '\0')
    {
      *p_intnum = val;
      res = 1;
    }
  }
  else /* max 10-digit decimal input */
  {
    while ( ( i < 11 ) && ( res != 1 ) )
    {
      if (p_inputstr[i] == '\0')
      {
        *p_intnum = val;
        /* return 1 */
        res = 1;
      }
      else if (((p_inputstr[i] == 'k') || (p_inputstr[i] == 'K')) && (i > 0))
      {
        val = val << 10;
        *p_intnum = val;
        res = 1;
      }
      else if (((p_inputstr[i] == 'm') || (p_inputstr[i] == 'M')) && (i > 0))
      {
        val = val << 20;
        *p_intnum = val;
        res = 1;
      }
      else if (ISVALIDDEC(p_inputstr[i]))
      {
        val = val * 10 + CONVERTDEC(p_inputstr[i]);
      }
      else
      {
        /* return 0, Invalid input */
        res = 0;
        break;
      }
      i++;
    }
  }
  return res;
}

u8 strs[]="123456";

Str2Int(strs,&Num);
printf("%d\r\n",Num);

方法二（转载另一位网友的）：

这里给出原文地址：https://blog.csdn.net/second60/article/details/80503335

int str2int1( char* str)
{
    int temp = 0;
    const char* p = str;
    if(str == NULL) return 0;
    if(*str == '-' || *str == '+')
    {
        str ++;
    }
    while( *str != 0)
    {
        if( *str < '0' || *str > '9')
        {
            break;
        }
        temp = temp*10 +(*str -'0');
        str ++;
    }
    if(*p == '-')
    {
        temp = -temp;
    }
    return temp;
}