实现itoa()

上代码之前先讲个笑话：曾经有位面试官问：“你实现过 唉踢哦诶（音） 吗”？　　我第一个想到的是各种OA系统，心想那玩意不多是Java实现的吗。。。过一会想明白了，瞬间石化。。。

#include <cstdio>
#include <stdint.h>

int8_t Myitoa(int64_t In_i64SrcNum, uint8_t In_i8Radix, char *In_pcDst)
{
    int8_t      i8RetVal    = 0;
    //这里强转是为了2、8、16进制显示的时候不需要符号
    uint64_t    ui64SrcNum  = (uint64_t)In_i64SrcNum;
    char        *pcDst      = In_pcDst;
    const char  acTable[]   = "0123456789ABCDEF";

    if (In_i8Radix <= 0 || pcDst == NULL)
    {
        i8RetVal = -1;
        goto fun_ret;
    }

    if (ui64SrcNum == 0)
    {
        *(pcDst ++) = '0';
        *pcDst      = 0;
        goto fun_ret;
    }

    if ((int64_t)ui64SrcNum < 0 && In_i8Radix == 10)
    {
        ui64SrcNum   = ~ui64SrcNum + 1;
        *(pcDst ++) = '-';
    }

    do //do...while循环的效率较高
    {
        *(pcDst ++) = acTable[ui64SrcNum % In_i8Radix];
        ui64SrcNum   /= In_i8Radix;
    } while (ui64SrcNum);
    *pcDst = 0;
    pcDst --;

    In_pcDst = *In_pcDst == '-' ? In_pcDst + 1 : In_pcDst;
    do 
    {
        char cTmp   = *In_pcDst;
        *In_pcDst   = *pcDst;
        *pcDst      = cTmp;
        In_pcDst ++;
        pcDst --;
    } while (In_pcDst < pcDst);

fun_ret:
    return i8RetVal;
}

void main()
{
    int64_t i64Test = -1;
    char    acBinStr[68] = {0};
    char    acOctStr[28] = {0};
    char    acDecStr[24] = {0};
    char    acHexStr[20] = {0};
    Myitoa(i64Test, 2, acBinStr);
    Myitoa(i64Test, 8, acOctStr);
    Myitoa(i64Test, 10, acDecStr);
    Myitoa(i64Test, 16, acHexStr);
    printf("%s\n%s\n%s\n%s\n", acBinStr, acOctStr, acDecStr, acHexStr);
    return;
}

趁着找工作这段时间，补补基础，唉，不是科班出身的短板啊。。。

参考：

http://www.cnblogs.com/applebunny/archive/2012/06/21/2557361.html

http://blog.csdn.net/wwwsq/article/details/5137006