86 lines
3.0 KiB
C++
86 lines
3.0 KiB
C++
#include <iostream>
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#include <bitset>
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#include <cstring>
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// 问题：将一个二进制流转换成可阅读的字符串，字符串为：大写字母加数字，去除0和O，I和1相近字符。
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const int g_bitNum = 5;
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const char* g_Coder = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789";
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int Encode(const char* pData, int nLen, char* res)
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{
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int totalLen = nLen * 8;
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int resLen = totalLen / g_bitNum;
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if (totalLen % g_bitNum != 0) ++resLen;
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if (res == nullptr) {
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return resLen;
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}
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for (int i = 0; i < resLen; ++i) {
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unsigned char nIndex = 0;
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int index = i * g_bitNum;
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for (int j = 0; j < g_bitNum && index + j < totalLen; ++j) {
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// bitValue 这一行只管取出下一位的值，放在哪里不管。
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// index 是连续的（相当于大组里面内增，换个大组继续内增）
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// index / 8 或者 index % 8 就是锁定第几组char的第几个，移动到最低位取出。
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unsigned char bitValue = ((pData[index / 8] >> (7 - index % 8)) & 1);
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// value 这一行只管把值放到对应的位置，与上面不要联系。
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// 这里对 value 高位到低位的放
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nIndex |= (bitValue << (g_bitNum - 1 - j));
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// 关键点：value 和 bitValue 各管各的。
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++index;
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}
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res[i] = g_Coder[nIndex];
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}
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res[resLen] = '\0';
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return resLen;
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}
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int Decode(const char* pData, unsigned char* res)
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{
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int len = static_cast<int>(std::strlen(pData));
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int codeBitCount = len * g_bitNum;
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int resCnt = codeBitCount / 8;
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if (res == nullptr) {
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return resCnt;
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}
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std::memset(res, 0, resCnt * sizeof(char));
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for (int i = 0; i < len; ++i) {
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const char key = pData[i];
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int nIndex = static_cast<int>(std::strchr(g_Coder, key) - g_Coder);
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for (int j = 0; j < g_bitNum && i * g_bitNum + j < codeBitCount; ++j) {
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// bitValue 这一行，只管取出每一位
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int bitValue = ((nIndex >> (g_bitNum - 1 - j)) & 1);
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// nOffset 是原始数据位索引
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int nOffset = i * g_bitNum + j;
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res[nOffset / 8] |= (bitValue << (7 - nOffset % 8));
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}
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}
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return resCnt;
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}
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int main()
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{
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int data[] = {12345, 45678};
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std::cout << "Original Data Len: " << sizeof(data) << std::endl;
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char* szEncode = nullptr;
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int size = Encode((const char*)data, sizeof(data), szEncode);
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std::printf("Encode Data Len: %d\n", size);
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szEncode = new char[size + 1];
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Encode((const char*)data, sizeof(data), szEncode);
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std::printf("Encode Data: %s\n", szEncode);
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unsigned char * szDecode = nullptr;
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int osize = Decode((const char *)szEncode, szDecode);
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std::printf("Decode Data Len: %d\n", osize);
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szDecode = new unsigned char [osize + 1];
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Decode((const char*)szEncode, szDecode);
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int* pInt = (int *)szDecode;
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std::printf("Int[0]:%d, Int[1]:%d\n", pInt[0], pInt[1]);
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delete[] szDecode;
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delete[] szEncode;
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return 0;
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} |